Refactor PR template based on feedback (#2865) (#2874)

Updated based on feedback received during sprint demo.

Backport of #2865

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,34 +1,14 @@
-<!--
+### Description
-See http://loopback.io/doc/en/contrib/triaging-pull-requests.html to understand
-the MINIMUM requirements for submitting pull requests.
--->
-
-### Type of change
-
-<!--
-See http://semver.org/ for more info.
--->
-
-- [ ] SEMVER-MAJOR -- Backwards-incompatible changes
-- [ ] SEMVER-MINOR -- Add functionality in a backwards-compatible manner
-- [ ] SEMVER-PATCH -- Backwards-compatible bug fixes
-
-### Description of change(s)
 
 
+#### Related issues (eg. strongloop/loopback#49)
 
-### Link(s) to related GitHub issues
+- None
-
-
 
 ### Checklist
 
 - [ ] CLA signed
-- [ ] Commit message conforms with the [Git commit message
-  guidelines](http://loopback.io/doc/en/contrib/git-commit-messages.html)
 - [ ] New tests are added to cover all changes
-- [ ] Code passes `npm test`
 - [ ] Code conforms with the [style
   guide](http://loopback.io/doc/en/contrib/style-guide.html)
-- [ ] All CI builds are passing (semi-required, left up to discretion of the
+- [ ] All CI builds are passing
-  reviewer)