docs(guide): grammar correction in security guide

Closes #16683

Author: craigdanj

docs/content/guide/security.ngdoc

@@ -102,7 +102,7 @@ For more information please visit {@link $http#json-vulnerability-protection JSO
 
 Bear in mind that calling `$http.jsonp` gives the remote server (and, if the request is not secured, any Man-in-the-Middle attackers)
 instant remote code execution in your application: the result of these requests is handed off
-to the browser as regular `<script>` tag.
+to the browser as a regular `<script>` tag.
 
 ## Strict Contextual Escaping