@used-by and @api tags are not recognized.

The @used-by and @api tags are not recognized by the plugin. And hence doesn't turn red. 

And I am new to open source so if it's not too much trouble can I try to fix it? The fix seems simple enough. A new line needs to be added at line 32 in PhpDoc.sublime-completions. I am still getting the hang of all the pull request and merging. So I can try to do id. Thanks.
