[Documentation:Plagiarism] Add PR template to Lichen (#35)

* Add PR template

* Remove PR title message

Author: sbelsk

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,13 @@
+### Please check if the PR fulfills these requirements:
+
+* [ ] Tests for the changes have been added/updated (if possible)
+* [ ] Documentation has been updated/added if relevant
+
+### What is the current behavior?
+<!-- List issue if it fixes/closes/implements one using the "Fixes #<number>" or "Closes #<number>" syntax -->
+
+### What is the new behavior?
+
+### Other information?
+<!-- Is this a breaking change? -->
+<!-- How did you test -->