Addng a PR Template

This template should contain all required information we want on a cop PR.

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,39 @@
+**Replace this text with a summary of the changes in your PR.
+The more detailed you are, the better.**
+
+-----------------
+Severity:
+[ ] - info
+[ ] - refactor
+[X] - convention (default)
+[ ] - warning
+[ ] - error
+[ ] - fatal
+-----------------
+
+**Wrong Code**
+
+```rb
+# Replace with an example of offending code for the cop. You can have multiple examples also.
+```
+
+**Correct Code**
+
+```rb
+# Replace with the expected correct code if the cop has an autocorrect. Else remove this part.
+```
+
+-----------------
+
+**Solidus PR Link:** # Replace with link to Solidus PR where the change has been made.
+
+-----------------
+
+**Before submitting the PR make sure the following are checked:**
+
+* [ ] The PR relates to *only* one cop with a clear title and description.
+* [ ] Feature branch is up-to-date with `master` (if not - rebase it).
+* [ ] Squashed related commits together.
+* [ ] Added tests.
+* [ ] Ran and ensured all tests are passing on a development environment.
+* [ ] If this is a new cop, added an entry for the cop on `/config/default.yml`