noted that regex_escape was added in 2.0

fixes #13759

docsite/rst/playbooks_filters.rst

@@ -526,6 +526,8 @@ To replace text in a string with regex, use the "regex_replace" filter::
 .. note:: Prior to ansible 2.0, if "regex_replace" filter was used with variables inside YAML arguments (as opposed to simpler 'key=value' arguments),
    then you needed to escape backreferences (e.g. ``\\1``) with 4 backslashes (``\\\\``) instead of 2 (``\\``).
 
+.. versionadded:: 2.0
+
 To escape special characters within a regex, use the "regex_escape" filter::
 
     # convert '^f.*o(.*)$' to '\^f\.\*o\(\.\*\)\$'