added pull request template (#74)

I thought it would be nice to have a pr template so I took inspiration
from the kubernetes one. This aims to have a more consistent process for
prs moving forward.

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,15 @@
+<!-- PR title template: [#ISSUE_NUMBER] <short description>
+     Example:           [#42] Solve problem X
+-->
+
+Resolves #PUT_ISSUE_NUMBER_HERE_IF_APPLICABLE
+
+<!--
+Write description of your changes here
+-->
+
+
+### Additional tasks
+
+- [ ] Documentation for changes provided/changed
+- [ ] Tests added