[docs] fix typo (#8180)

Author: josh-fnbtech

site/content/tutorial/02-reactivity/04-updating-arrays-and-objects/text.md

@@ -23,7 +23,7 @@ function addNumber() {
 }
 ```
 
-The same rule applies to array methods such as `pop`, `shift`, and `splice` and to objects methods such as `Map.set`, `Set.add`, etc.
+The same rule applies to array methods such as `pop`, `shift`, and `splice` and to object methods such as `Map.set`, `Set.add`, etc.
 
 Assignments to *properties* of arrays and objects — e.g. `obj.foo += 1` or `array[i] = x` — work the same way as assignments to the values themselves.
 
@@ -51,4 +51,4 @@ quox(obj);
 
 ...won't trigger reactivity on `obj.foo.bar`, unless you follow it up with `obj = obj`.
 
-A simple rule of thumb: the updated variable must directly appear on the left hand side of the assignment.
+A simple rule of thumb: the updated variable must directly appear on the left hand side of the assignment.