CONTRIBUTING: Split in categories

Signed-off-by: Maxime “pep” Buquet <pep@bouah.net>

README.md

@@ -53,34 +53,5 @@ Contributing
 
 Thank you for your interest in the project!
 
-We recommend you come and talk to us in the channel and/or open an issue
-before you start working on a feature, to see if it aligns with our goals.
-
-The library is still in development, and while this is the case we adopt a
-fail-fast strategy, which is also a reason for the choice of the language.
-
-The earlier we catch bugs and fix them, the less chances they have to confuse
-users of our library, or make end-users give up on software developed using
-this library. This also helps improving other software in the ecosystem.
-
-Code changes should try to include documentation as possible. They should also
-include tests where appropriate, and pass the existing test suite.
-
-CI should pass to submit your changes. This is done by ensuring `cargo fmt`
-and `cargo test` pass (in the workspace). Please do not run `cargo fmt` as a
-separate commit but do it as part of each of your commits.
-
-More thorough tests can be done locally with `act` or `forgejo-runner
-exec`, which is also what is run in the CI. We require docker to be setup for
-this to work.
-
-Merge requests can contain as many commits as necessary, but commits should be
-kept rather small and meaningful (not include too many different things).
-
-Do not forget to update changelogs and other crate metadata where necessary.
-
-Signing commits (`git commit -S`) and adding DCO bits (`git commit -s`) are
-welcome but not mandatory.
-
-We'll do our best to review and discuss changes with you but we're also humans
-with other activities, please be patient with us.
+Contributing rules are available as
+[CONTRIBUTING.md](https://gitlab.com/xmpp-rs/xmpp-rs/-/raw/main/CONTRIBUTING.md) in the repository.