Add inline documentation for the run_wptexturize filter.

Props miqrogroove for the original patch.
Fixes #19550.


git-svn-id: https://develop.svn.wordpress.org/trunk@28723 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/formatting.php

@@ -37,6 +37,18 @@ function wptexturize($text) {
 
 	// No need to set up these static variables more than once
 	if ( ! isset( $static_characters ) ) {
+		/**
+		 * Filter whether to skip running `wptexturize()`.
+		 *
+		 * Passing false to the filter will effectively short-circuit `wptexturize()`.
+		 * returning the original text passed to the function instead.
+		 *
+		 * The filter runs only once, the first time `wptexturize()` is called.
+		 *
+		 * @since 4.0.0
+		 *
+		 * @param bool $run_texturize Whether to short-circuit `wptexturize()`.
+		 */
 		$run_texturize = apply_filters( 'run_wptexturize', $run_texturize );
 		if ( false === $run_texturize ) {
 			return $text;