add template for pull requests

Author: xsuchy

.github/pull_request_template.md

@@ -0,0 +1,7 @@
+
+# Add a reference to related issue - preferably in the git commit message
+Fixes: #NUMBER
+
+# Add release note. See https://rpm-software-management.github.io/mock/Release-Notes-New-Entry
+# or let us know to add `label no-release-notes` if you think the change does
+# not deserve a release note.