TinyMCE: wptextpattern: add docs

Props DrewAPicture and iseulde.
See #31441.


git-svn-id: https://develop.svn.wordpress.org/trunk@32703 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/js/tinymce/plugins/wptextpattern/plugin.js

@@ -1,9 +1,29 @@
+/**
+ * Text pattern plugin for TinyMCE
+ *
+ * @since 4.3.0
+ *
+ * This plugin can automatically format text patterns as you type. It includes two patterns:
+ *  - Unordered list (`* ` and `- `).
+ *  - Ordered list (`1. ` and `1) `).
+ *
+ * If the transformation in unwanted, the user can undo the change by pressing backspace,
+ * using the undo shortcut, or the undo button in the toolbar.
+ */
 ( function( tinymce, setTimeout ) {
 	tinymce.PluginManager.add( 'wptextpattern', function( editor ) {
 		var $$ = editor.$,
 			patterns = [],
 			canUndo = false;
 
+		/**
+		 * Add a pattern to format with a callback.
+		 *
+		 * @since 4.3.0
+		 *
+		 * @param {RegExp}   regExp
+		 * @param {Function} callback
+		 */
 		function add( regExp, callback ) {
 			patterns.push( {
 				regExp: regExp,