Merge pull request #686 from trombik/issue-685

chore: introduce PULL_REQUEST_TEMPLATE.md

Author: trombik

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,14 @@
+**IMPORTANT**: Please **do not create a Pull Request** without
+[creating an issue](https://github.com/UncleRus/esp-idf-lib/issues/new/choose)
+first.
+
+Include `fixes` or other supported keywords that links a PR to an
+issue in either a commit log or the PR. See
+[Linking a pull request to an issue using a keyword](https://docs.github.com/en/issues/tracking-your-work-with-issues/using-issues/linking-a-pull-request-to-an-issue#linking-a-pull-request-to-an-issue-using-a-keyword)
+for the keywords.
+
+Make sure your branch is up-to-date with the latest `master` branch. If it is
+not, do `git rebase master`.
+
+After creating a PR, make sure all the tests in the CI pass. If you cannot
+understand why a test fails, ask for help.