docs: decision record about renaming git branches

docs/development/decision-records/2023-04-03_renaming_branches/README.md

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+# Renaming Git branches to comply with TractusX standards
+
+## Decision
+
+TractusX-EDC will rename its Git branching structure to comply with TractusX release guidelines, and to be able to
+leverage
+GitHub convenience features, while continuing to use the Gitflow branching model.
+
+## Rationale
+
+The TractusX organization has established
+a [release guideline](https://eclipse-tractusx.github.io/docs/release/trg-2/trg-2-1/) which mandates that all projects'
+default branch be called `main`.
+
+### Selecting default branches
+
+In GitHub, the default branch has a couple of important features attached to it:
+
+- cloning or forking the repository will automatically check out the default branch
+- when creating pull requests the default branch is targeted by default
+- [automatic issue linking and closing](https://docs.github.com/en/issues/tracking-your-work-with-issues/linking-a-pull-request-to-an-issue)
+  only works with the default branch
+
+### The problem with GitFlow
+
+The GitFlow branching model suggests that the day-to-day work be done on a branch called `develop`, while the `main`
+branch stores the version history and only receives (merge) commits after a version releases.
+
+This would call for `develop` being the GitHub default branch, which is forbidden by the aforementioned release
+guideline.
+
+## Approach
+
+In order to comply with the TractusX release guideline, to make use of the GitHub features _and_ also use GitFlow, we
+propose renaming a couple of branches. While GitFlow _suggests_ branch names, it does not _require_ it, and most
+tools allow for customizing them anyway. Thus, from an abstract perspective, the following changes are necessary:
+
+- `main` becomes our work/development branch. All pull requests target `main`.
+- `develop` gets deleted
+- a new branch `releases` is introduced, which tracks the release history and receives post-release merge commits.
+
+Technically this will involve force-pushing, which is a potentially destructive operation. Therefor the following
+section outlines the exact sequence of steps. Note that "upstream" refers to `eclipse-tractusx/tractusx-edc`, while "
+fork" refers to `catenax-ng/tx-tractusx-edc`.
+
+- create a new branch `upstream/releases`
+- create a new branch `fork/releases`, set it to track `upstream/releases`
+- push the contents of `fork/main` -> `upstream/releases`
+- synchronize `upstream/develop` with `fork/develop`
+- force-push the contents of `develop` -> `upstream/main` (do **not** update the tracking branch!)
+- synchronize `upstream/main` -> `fork/main`
+- delete/archive `upstream/develop` and `fork/develop`
+
+_Note that most of this will likely need to be done manually, since GitHub does not allow for advanced Git operations
+like force-pushing. Write access to `upstream` is required!_
+
+## Further notes
+
+The new `releases` branch (note the plural) will serve the same purpose that `main` did up until now, which is to track
+all releases (via merge commits and tags) in chronological order. We will continue to have separate `release/x.y.z`
+branches for every release.