Adding PULL_REQUEST_TEMPLATE.md (#2265)

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,23 @@
+<!--  Thanks for sending a pull request! We request you provide detailed description as much as possible. -->
+
+## Description
+<!--- Describe your changes in detail. -->
+<!-- Typically try to give details of what, why and how of the PR changes. -->
+
+## Which issue(s) this PR fixes:
+<!--
+*Automatically closes linked issue when PR is merged.
+Usage: `Fixes #<issue number>`, or `Fixes (paste link of issue)`.
+-->
+Fixes #
+
+## Testing
+<!--- Please describe in detail how you tested your changes. -->
+
+## Checklist:
+<!-- Please tick following checkboxes as per your understanding. -->
+- [ ] I ran tests as well as code linting locally to verify my changes. 
+- [ ] I have done manual verification of my changes, changes working as expected.
+- [ ] I have added new tests to cover my changes.
+- [ ] My changes follow contributing guidelines of Fission.
+- [ ] I have signed all of my commits.