[docs] Fix "Edit this page" link (#19170)

Author: nelopuchades

docs/src/modules/components/useMarkdownDocs.js

@@ -143,7 +143,7 @@ ${headers.components
               key={content}
               demo={demos[name]}
               demoOptions={demoOptions}
-              githubLocation={`${SOURCE_CODE_ROOT_URL}/${name}`}
+              githubLocation={`${SOURCE_CODE_ROOT_URL}/docs/src/${name}`}
             />
           );
         }

docs/src/modules/constants.js

@@ -52,7 +52,7 @@ const LANGUAGES_LABEL = [
   },
 ];
 
-const SOURCE_CODE_ROOT_URL = 'https://github.com/mui-org/material-ui/blob/master/docs/src';
+const SOURCE_CODE_ROOT_URL = 'https://github.com/mui-org/material-ui/blob/master';
 
 module.exports = {
   CODE_VARIANTS,

docs/src/modules/utils/generateMarkdown.js

@@ -3,9 +3,8 @@ import * as recast from 'recast';
 import { parse as docgenParse } from 'react-docgen';
 import { Router as Router2 } from 'next/router';
 import { pageToTitle } from './helpers';
-import { LANGUAGES_IN_PROGRESS } from 'docs/src/modules/constants';
+import { SOURCE_CODE_ROOT_URL, LANGUAGES_IN_PROGRESS } from 'docs/src/modules/constants';
 
-const SOURCE_CODE_ROOT_URL = 'https://github.com/mui-org/material-ui/blob/master';
 const PATH_REPLACE_REGEX = /\\/g;
 const PATH_SEPARATOR = '/';
 const DEMO_IGNORE = LANGUAGES_IN_PROGRESS.map(language => `-${language}.md`);