Correct PR template grammar

Author: michplunkett

.github/pull_request_template.md

@@ -1,6 +1,6 @@
 <!---
 Please write your PR name in the present imperative tense. Examples of that tense are:
-"Fix issue in the dispatcher where…", "Improve our handling of…", etc."
+"Fix issue in the dispatcher where…", "Improve our handling of…", etc.
 
 For more information on Pull Requests, you can reference here:
 https://success.vanillaforums.com/kb/articles/228-using-pull-requests-to-contribute