[skip ci] Create PULL_REQUEST_TEMPLATE.md

Author: kostrykin

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,9 @@
+<!--
+
+CREATE THE PULL REQUEST AS A DRAFT,
+then CI will only run the test suite.
+
+When the test suite passes, mark the PR as ready for review.
+This will run the regression tests. Trigger CI commit might be required.
+
+-->