docs: rearrange paths, update links and redirects

Part-of: <https://dev.funkwhale.audio/funkwhale/funkwhale/-/merge_requests/2353>

docs/developer/workflows/git.md

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+# Git workflow
+
+Funkwhale uses GitLab's merge requests to manage changes. The workflow looks like this:
+
+1. Assign the issue you are working on to yourself, or create one if it doesn't exist
+2. Create a fork of the project
+3. Check out the `develop` branch. If you're making a minor change (such as fixing a typo) you can check out the `stable` branch
+4. Create a new branch based on the checked out branch. Make sure to give your branch a meaningful name and include the issue number if required
+5. Work on your changes locally. Try to keep each commit small to make reviews easier
+6. Add a changelog fragment summarizing your changes
+7. Lint the codebase using the following command:
+
+   ::::{tab-set}
+
+   :::{tab-item} API code
+
+   ```sh
+   black --check --diff . # Run the black linter in the project root to highlight any new issues
+   ```
+
+   :::
+
+   :::{tab-item} Frontend code
+
+   ```sh
+   cd front
+   yarn run eslint # Run eslint in the front directory
+   ```
+
+   :::
+
+   ::::
+
+8. Push your branch
+9. Create a merge request in the GitLab frontend
+10. We'll review your request and feed back
+
+```{mermaid}
+%%{init: { 'gitGraph': {'mainBranchName': 'stable'} } }%%
+    gitGraph
+        commit
+        branch develop
+        commit
+        commit
+        branch feature
+        commit
+        commit
+        checkout develop
+        merge feature
+        commit
+        checkout stable
+        merge develop
+```