repo: expand on CONTRIBUTING.md about PRs

CONTRIBUTING.md

@@ -82,6 +82,33 @@ If you want to contribute art or the like, do that in whatever **you** are most
 - Agreement must be based on [informed consent].
   - In effect, a maintainer has to understand what they agree to.
 
+# Interacting with PRs
+
+> [!NOTE] Remember, be respectful.
+> Entities invest their free time and motivation into making these changes,
+> treat them appropiately.
+
+- Since in iOwO, we mostly work based on forks, [git's remotes] work fairly good.
+- Replace things in pointy brackets (`<>`) respectively (and remove the pointy brackets).
+
+## Initial steps for a new contributor or new local checkout
+
+```sh
+git remote add <contributor-name> https://forge.katzen.cafe/<contributor-account>/iowo.git
+git remote update <contributor-name>
+```
+
+## After setting up the remote
+
+- You can repeat this step anytime you want to switch branches or update your local checkout.
+- The PR branch is visible just below the PR title on forgejo, after the colon (`:`).
+
+```sh
+git switch <pr-branch>
+git pull
+```
+
+
 [code of conduct]: ./CODE_OF_CONDUCT.md
 [informed consent]: https://en.wikipedia.org/wiki/Informed_consent
-
+[git's remotes]: https://git-scm.com/docs/git-remote