[Docs] Add markdownlint for documentation formatting consistency

Author: bmish

.markdownlint.json

@@ -0,0 +1,3 @@
+{
+  "line-length": false
+}

.markdownlintignore

@@ -0,0 +1,3 @@
+CHANGELOG.md
+LICENSE
+node_modules

README.md

@@ -1,4 +1,6 @@
+<!-- markdownlint-disable-next-line MD033-->
 # `eslint-plugin-react` <sup>[![Version Badge][npm-version-svg]][package-url]</sup>
+
 ===================
 
 [![github actions][actions-image]][actions-url]
@@ -8,16 +10,15 @@
 
 React specific linting rules for `eslint`
 
-# Installation
+## Installation
 
 ```sh
-$ npm install eslint eslint-plugin-react --save-dev
+npm install eslint eslint-plugin-react --save-dev
 ```
 
 It is also possible to install ESLint globally rather than locally (using npm install eslint --global). However, this is not recommended, and any plugins or shareable configs that you use must be installed locally in either case.
 
-# Configuration
-
+## Configuration
 
 Use [our preset](#recommended) to get reasonable defaults:
 
@@ -109,7 +110,7 @@ Enable the rules that you would like to use.
   }
 ```
 
-# List of supported rules
+## List of supported rules
 
 ✔: Enabled in the [`recommended`](#recommended) configuration.\
 🔧: Fixable with [`eslint --fix`](https://eslint.org/docs/user-guide/command-line-interface#fixing-problems).\
@@ -179,7 +180,7 @@ Enable the rules that you would like to use.
 |  |  |  | [react/void-dom-elements-no-children](docs/rules/void-dom-elements-no-children.md) | Disallow void DOM elements (e.g. `<img />`, `<br />`) from receiving children |
 <!-- AUTO-GENERATED-CONTENT:END -->
 
-## JSX-specific rules
+### JSX-specific rules
 
 <!-- AUTO-GENERATED-CONTENT:START (JSX_RULES) -->
 | ✔ | 🔧 | 💡 | Rule | Description |
@@ -225,15 +226,15 @@ Enable the rules that you would like to use.
 |  | 🔧 |  | [react/jsx-wrap-multilines](docs/rules/jsx-wrap-multilines.md) | Disallow missing parentheses around multiline JSX |
 <!-- AUTO-GENERATED-CONTENT:END -->
 
-## Other useful plugins
+### Other useful plugins
 
 - Rules of Hooks: [eslint-plugin-react-hooks](https://github.com/facebook/react/tree/master/packages/eslint-plugin-react-hooks)
 - JSX accessibility: [eslint-plugin-jsx-a11y](https://github.com/evcohen/eslint-plugin-jsx-a11y)
 - React Native: [eslint-plugin-react-native](https://github.com/Intellicode/eslint-plugin-react-native)
 
-# Shareable configurations
+## Shareable configurations
 
-## Recommended
+### Recommended
 
 This plugin exports a `recommended` configuration that enforces React good practices.
 
@@ -247,7 +248,7 @@ To enable this configuration use the `extends` property in your `.eslintrc` conf
 
 See [`eslint` documentation](https://eslint.org/docs/user-guide/configuring/configuration-files#extending-configuration-files) for more information about extending configuration files.
 
-## All
+### All
 
 This plugin also exports an `all` configuration that includes every available rule.
 This pairs well with the `eslint:all` rule.
@@ -263,11 +264,10 @@ This pairs well with the `eslint:all` rule.
 
 **Note**: These configurations will import `eslint-plugin-react` and enable JSX in [parser options](https://eslint.org/docs/user-guide/configuring/language-options#specifying-parser-options).
 
-# License
+## License
 
 `eslint-plugin-react` is licensed under the [MIT License](https://opensource.org/licenses/mit-license.php).
 
-
 [npm-url]: https://npmjs.org/package/eslint-plugin-react
 [npm-image]: https://img.shields.io/npm/v/eslint-plugin-react.svg
 

SECURITY.md

@@ -9,7 +9,6 @@ This is the list of versions of `eslint-plugin-react` which are currently being
 | 7.x      | :white_check_mark: |
 | < 7.x    | :x:                |
 
-
 ## Reporting a Vulnerability
 
 To report a security vulnerability, please use the [Tidelift security contact](https://tidelift.com/security). Tidelift will coordinate the fix and disclosure.

docs/rules/boolean-prop-naming.md

@@ -36,6 +36,7 @@ var Hello = createReactClass({
   render: function() { return <div />; };
 });
 ```
+
 ```jsx
 type Props = {
   isEnabled: boolean
@@ -94,8 +95,8 @@ The custom message to display upon failure to match the rule. This overrides the
 
 If you choose to use a custom message, you have access to two template variables.
 
-* `propName` – the name of the prop that does not match the pattern
-* `pattern` – the pattern against which all prop names are tested
+- `propName` – the name of the prop that does not match the pattern
+- `pattern` – the pattern against which all prop names are tested
 
 For example, if a prop is named `something`, and if the rule's pattern is set to `"^(is|has)[A-Z]([A-Za-z0-9]?)+"`, you could set the custom message as follows:
 
@@ -105,7 +106,7 @@ message: 'It is better if your prop ({{ propName }}) matches this pattern: ({{ p
 
 And the failure would look like so:
 
-```
+```plaintext
 It is better if your prop (something) matches this pattern: (^is[A-Z]([A-Za-z0-9]?)+)
 ```
 

docs/rules/default-props-match-prop-types.md

@@ -192,7 +192,7 @@ If you don't care about stray `defaultsProps` in your components, you can disabl
 
 - [require-default-props](./require-default-props.md)
 
-# Resources
+## Resources
 
 - [Official React documentation on defaultProps](https://facebook.github.io/react/docs/typechecking-with-proptypes.html#default-prop-values)
 

docs/rules/destructuring-assignment.md

@@ -3,6 +3,7 @@
 🔧 This rule is automatically fixable using the `--fix` [flag](https://eslint.org/docs/latest/user-guide/command-line-interface#--fix) on the command line.
 
 Rule can be set to either of `always` or `never`;
+
 ```js
 "react/destructuring-assignment": [<enabled>, 'always']
 ```

docs/rules/iframe-missing-sandbox.md

@@ -2,7 +2,7 @@
 
 The sandbox attribute enables an extra set of restrictions for the content in the iframe. Using sandbox attribute is considered a good security practice.
 
-See https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe#attr-sandbox
+See <https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe#attr-sandbox>
 
 ## Rule Details
 

docs/rules/jsx-curly-brace-presence.md

@@ -32,7 +32,7 @@ or alternatively
 ...
 ```
 
-### Valid options for <string>
+### Valid options for `<string>`
 
 They are `always`, `never` and `ignore` for checking on JSX props and children.
 
@@ -45,7 +45,7 @@ If passed in the option to fix, this is how a style violation will get fixed
 * `always`: wrap a JSX attribute in curly braces/JSX expression and/or a JSX child the same way but also with double quotes
 * `never`: get rid of curly braces from a JSX attribute and/or a JSX child
 
-- All fixing operations use double quotes.
+* All fixing operations use double quotes.
 
 For examples:
 
@@ -78,6 +78,7 @@ They can be fixed to:
 ```
 
 Examples of **incorrect** code for this rule, when configured with `{ props: "always", children: "always", "propElementValues": "always" }`:
+
 ```jsx
 <App prop=<div /> />;
 ```
@@ -89,6 +90,7 @@ They can be fixed to:
 ```
 
 Examples of **incorrect** code for this rule, when configured with `{ props: "never", children: "never", "propElementValues": "never" }`:
+
 ```jsx
 <App prop={<div />} />;
 ```
@@ -115,6 +117,7 @@ Examples of **incorrect** code for this rule, when configured with `"always"`:
 ```
 
 They can be fixed to:
+
 ```jsx
 <App>{"Hello world"}</App>;
 <App prop={"Hello world"} attr={"foo"}>{"Hello world"}</App>;
@@ -152,7 +155,6 @@ will be warned and fixed to:
 
 For example:
 
-
 ```jsx
 <App prop='Hello "foo" world'>Hello 'foo' "bar" world</App>;
 ```

docs/rules/jsx-curly-newline.md

@@ -18,6 +18,7 @@ This rule accepts either an object option:
   singleline: "consistent" | "forbid" | "require", // default to 'consistent'
 }
 ```
+
 Option `multiline` takes effect when the jsx expression inside the curlies occupies multiple lines.
 
 Option `singleline` takes effect when the jsx expression inside the curlies occupies a single line.
@@ -143,7 +144,6 @@ Examples of **correct** code for this rule:
 </div>
 ```
 
-
 ## When Not To Use It
 
 You can turn this rule off if you are not concerned with the consistency of padding linebreaks inside of JSX attributes or expressions.