Merge bitcoin#17772: doc: Mention PR Club in CONTRIBUTING.md

34d826e doc: Mention PR Club in CONTRIBUTING.md (Emil Engler)

Pull request description:

  As we have a ["Review Club"](https://github.com/bitcoin/bitcoin/labels/Review%20club) label it would be worth mentioning it in the CONTRIBUTING.md file for beginners.

ACKs for top commit:
  practicalswift:
    ACK 34d826e -- The Bitcoin Core PR Review Club is a great effort to introduce new contributors to the project in a positive and friendly way! We need that kind of newcomer friendly on-ramps to attract and educate the next generation of contributors! Kudos to @ jnewbery for helping secure the project also in the super long-term :)

Tree-SHA512: 9c6cbe9a82e1f13db10ad19c50a55566dbe3f5ccaf5b91f75c5a743f7f4f690515274d64c132460791bd4d8e76255b5cbfb2877908459734b52e3fbdba71fbb3

Author: MarcoFalke

CONTRIBUTING.md

@@ -16,7 +16,7 @@ release cycle, overall merging, moderation and appointment of maintainers.
 
 If you're looking for somewhere to start contributing, check out the
 [good first issue](https://github.com/bitcoin/bitcoin/issues?q=is%3Aopen+is%3Aissue+label%3A%22good+first+issue%22)
-list.
+list or participate in a weekly [Bitcoin Core PR Review Club](https://bitcoincore.reviews/) meeting.
 
 Communication Channels
 ----------------------