adds pull request template (#16)

Closes #15.

pull_request_template.md

@@ -0,0 +1,15 @@
+<!-- IMPORTANT!!! Aside from typographical corrections and minor changes, please consider creating an Issue before making a Pull Request. -->
+
+### Description
+Please include a one to two sentence description that summarizes the issue and your solution.
+
+### Related Issue(s)
+Use Github keywords to link your PR to the related Issue(s). For more information on Github keywords please visit [Github's documentation](https://docs.github.com/en/get-started/writing-on-github/working-with-advanced-formatting/using-keywords-in-issues-and-pull-requests#linking-a-pull-request-to-an-issue)
+
+Example:
+
+`Resolves #100`
+
+### Testing
+Describe how you tested this PR. Include step by step instructions for others to test this PR.
+Be detailed and include images where appropriate.