doc: Explain that anyone can work on good first issues, move text to CONTRIBUTING.md

Author: MarcoFalke

.github/ISSUE_TEMPLATE/good_first_issue.md

@@ -7,15 +7,14 @@ assignees: ''
 
 ---
 
+<!-- A good first issue is an uncontroversial issue, that has a relatively unique and obvious solution -->
+
+<!-- Motivate the issue and explain the solution briefly -->
 
 #### Useful skills:
 
 <!-- (For example, “C++11 std::thread”, “Qt5 GUI and async GUI design” or “basic understanding of Bitcoin mining and the Bitcoin Core RPC interface”.) -->
 
 #### Want to work on this issue?
 
-The purpose of the `good first issue` label is to highlight which issues are suitable for a new contributor without a deep understanding of the codebase.
-
-You do not need to request permission to start working on this. You are encouraged to comment on the issue if you are planning to work on it. This will help other contributors monitor which issues are actively being addressed and is also an effective way to request assistance if and when you need it.
-
 For guidance on contributing, please read [CONTRIBUTING.md](https://github.com/bitcoin/bitcoin/blob/master/CONTRIBUTING.md) before opening your pull request.

CONTRIBUTING.md

@@ -39,6 +39,19 @@ unsure, you might want to leave a comment on the issue first.
 You may also participate in the weekly
 [Bitcoin Core PR Review Club](https://bitcoincore.reviews/) meeting.
 
+### Good First Issue Label
+
+The purpose of the `good first issue` label is to highlight which issues are
+suitable for a new contributor without a deep understanding of the codebase.
+
+However, good first issues can be solved by anyone. If they remain unsolved
+for a longer time, a frequent contributor might address them.
+
+You do not need to request permission to start working on an issue. However,
+you are encouraged to leave a comment if you are planning to work on it. This
+will help other contributors monitor which issues are actively being addressed
+and is also an effective way to request assistance if and when you need it.
+
 Communication Channels
 ----------------------