chore: update pull request template (#373)

* chore: rename pull request action file name

* chore: add pull request template md file

Co-authored-by: alex chow <zhouchuanglin@gmail.com>

Author: ArgoZhang

.github/pull_request_template.md

@@ -0,0 +1,16 @@
+# {PR title}
+
+<!-- Thank you for submitting a pull request to our repo. -->
+
+<!-- If this is your first PR in the ASP.NET Core repo, please run through the checklist
+below to ensure a smooth review and merge process for your PR. -->
+
+<!-- Once all that is done, you're ready to go. Open the PR with the content below. -->
+
+Summary of the changes (Less than 80 chars)
+
+## Description
+
+{Detail}
+
+Fixes #{bug number}