Update pull request template to use github "closes" keyword (#130)

* Update pull request template to use github "closese" keyword

* Add article link

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,7 +1,16 @@
 ### Description
 
 
+<!-- 
+
+If your pull request closes any issues, add them below with the `closes` keyword before them 
+
+Example: closes #101
+
+See the following article for more information: https://docs.github.com/en/free-pro-team@latest/github/managing-your-work-on-github/linking-a-pull-request-to-an-issue#linking-a-pull-request-to-an-issue-using-a-keyword
+
+-->
 
 ### Closes issues
 
-- #
+- closes #