Stop documenting 'filter' as an available field (#644)

Co-authored-by: Claude <noreply@anthropic.com>

Author: swissspidy

README.md

@@ -3837,7 +3837,6 @@ These fields are optionally available:
 * post_type
 * post_mime_type
 * comment_count
-* filter
 * url
 
 **EXAMPLES**
@@ -8703,7 +8702,6 @@ These fields are optionally available:
 * caps
 * cap_key
 * allcaps
-* filter
 * url
 
 **EXAMPLES**

src/Post_Command.php

@@ -874,7 +874,6 @@ protected function delete_callback( $post_id, $assoc_args ) {
 	 * * post_type
 	 * * post_mime_type
 	 * * comment_count
-	 * * filter
 	 * * url
 	 *
 	 * ## EXAMPLES

src/User_Command.php

@@ -115,7 +115,6 @@ public function __construct() {
 	 * * caps
 	 * * cap_key
 	 * * allcaps
-	 * * filter
 	 * * url
 	 *
 	 * ## EXAMPLES