Add pull request template

Signed-off-by: Gilles Peskine <[email protected]>

.github/pull_request_template.md

@@ -0,0 +1,29 @@
+## Description
+
+Please write a few sentences describing the overall goals of the pull request's commits.
+
+
+
+## PR checklist
+
+Please add the numbers of the associated pull requests for consuming branches
+(a link is fine). For the time being, even if a change is only needed in one
+branch, a pull request is needed in all branches so that the CI can validate
+the change as non-harmful.
+
+- [ ] **development PR** Mbed-TLS/mbedtls#
+- [ ] **3.6 PR** Mbed-TLS/mbedtls#
+
+
+
+## Notes for the submitter
+
+Please refer to the [contributing guidelines](https://github.com/Mbed-TLS/mbedtls/blob/development/CONTRIBUTING.md), especially the
+checklist for PR contributors.
+
+Help make review efficient:
+* Multiple simple commits
+  - please structure your PR into a series of small commits, each of which does one thing
+* Avoid force-push
+  - please do not force-push to update your PR - just add new commit(s)
+* See our [Guidelines for Contributors](https://mbed-tls.readthedocs.io/en/latest/reviews/review-for-contributors/) for more details about the review process.