Update usage.mdx (#3256)

* Update usage.mdx

In the "Content" section the "Label text" that is used in the examples is referred to as "Heading" which is confusing. Attempting to clarify label vs action text with this proposed edit.

* Update usage.mdx

Changing "can" to "must" since the label is required for accessibility.

* chore(format): fix format error

Co-authored-by: TJ Egan <tw15egan@gmail.com>

src/pages/components/toggle/usage.mdx

@@ -97,19 +97,20 @@ user “flips the switch”. They are commonly used for “on/off” switches.
 
 ## Content
 
-#### Heading
+#### Label text
 
-A heading may accompany a toggle to further clarify on the action the toggle
-will perform.
+Label text must accompany a toggle to further clarify the action that the toggle
+performs.
 
-#### Labels
+#### Action text
 
-Use labels with a toggle so the action is clear. Labels should be three words or
-less and appear on the side of a toggle.
+Use text to describe the binary action of toggle so that the action is clear.
+Action text must be three words or less and is displayed on the side of a
+toggle.
 
 #### Language
 
-Use adjectives rather than verbs to describe labels and the state of the object
+Use adjectives rather than verbs to describe actions and the state of the object
 affected.
 
 ## Variants