PR template additions

Board PRs require a few more checks.
+ Changes from review comments (see original PR).

- Add link to TESTS-folder
- Mbed Enabled in capitals + link
- Add line changes.
  - GitHub shows the content otherwise very strangely.
- Re-order, line also after board enablements.
- PR review changes per feedback from Pekka Niskanen
- Add notes on issues to Mbed OS & Client
  - Maintainers update the hashes, but in order to get the issues
    fixed in the 1st place -> issues need to get reported.

Author: Janne Kiiskilä

.github/pull_request_template.md

@@ -1,12 +1,3 @@
-<!--
-
-For more information on the requirements for pull requests, please see [the CONTRIBUTING.md](CONTRIBUTING.md).
-
--->
-
-[] I confirm this contribution is my own and I agree to license it with Apache 2.0.
-[] I confirm the moderators may change the PR before merging it in.
-
 ### Summary of changes <!-- Required -->
 
 <!--
@@ -21,3 +12,24 @@ For more information on the requirements for pull requests, please see [the CONT
     Write good, descriptive Git commit messages.
 
 -->
+
+<!--
+
+For more information on the requirements for pull requests, please see [the CONTRIBUTING.md](CONTRIBUTING.md).
+
+-->
+
+[] I confirm this contribution is my own and I agree to license it with Apache 2.0.
+
+[] I confirm the moderators may change the PR before merging it in.
+
+For new board enablements only:
+
+[] I confirm the board is [Mbed Enabled](https://www.mbed.com/en/about-mbed/mbed-enabled/introduction/) and passes the Mbed Enabled test set.
+
+[] I confirm the contribution has been tested properly and the tests results for [TESTS](https://github.com/ARMmbed/mbed-os-example-pelion/tree/master/TESTS) are attached.
+
+[] I confirm `mbed-os.lib` and `mbed-cloud-client.lib` hashes or the content in folders `mbed-os` and `mbed-cloud-client` were not modified in order to pass the tests.
+
+- Maintainers of this repository update the Mbed OS and Client hashes.
+- Please report any issues through issues in relevant repositories.