Forgejo development workflow

Fixes: https://codeberg.org/forgejo/forgejo/issues/5

Signed-off-by: Loïc Dachary <loic@dachary.org>

WORKFLOW.md

@@ -0,0 +1,65 @@
+Forgejo development workflow
+===
+
+Forgejo is a soft fork, i.e. a set of commits applied to the Gitea development branch and the stable branches. On a regular basis those commits are rebased and modified if necessary to keep working. All Forgejo commits are merged into a branch from which binary releases and packages are created and distributed. The development workflow is a set of conventions Forgejo developers are expected to follow to work together.
+
+# Naming conventions
+
+## Development
+
+* Gitea: main
+* Forgejo: forgejo
+* Integration: forgejo-integration
+* Feature branches: forgejo-feature-name
+
+## Stable
+
+* Gitea: release/vX.Y
+* Forgejo: vX.Y/forgejo
+* Integration: vX.Y/forgejo-integration
+* Feature branches: vX.Y/forgejo-feature-name
+
+# Rebasing
+
+## *Feature branch*
+
+The *Gitea* branches are mirrored with the Gitea development and stable branches.
+
+On a regular basis, each *Feature branch* is rebased against the base *Gitea* branch.
+
+## *Integration* and *Forgejo*
+
+The latest *Gitea* branch resets the *Integration* branch and all *Feature branches* are merged into it. 
+
+If tests pass, the *Forgejo* branch is reset to the tip of the *Integration* branch.
+
+If tests do not pass, an issue is filed to the *Feature branch* that fails the test. Once the issue is resolved, another round of rebasing starts.
+
+# Releasing
+
+When a tag is set to a *Stable* *Forgejo* branch, the CI pipeline creates and uploads binaries and packages.
+
+# Feature branches
+
+All *Feature branches* are based on the \*forgejo-development branch which provides the Woodpecker CI configuration and other development tools.
+
+The purpose of each *Feature branch* is documented in CONTRIBUTING.md as follows:
+
+* Name of the *Feature branch* and name of the base *Feature branch* (for instance forgejo-federation based on forgejo-development)
+    * Backports: list of the versions in which this *Feature branch* is supported (for instance v1.18, v1.19)
+    * Description: explains what the focus of the *Feature branch* is (for instance: forge federation features)
+
+# Contributing
+
+Most people who are used to contributing will be familiar with the workflow of sending a pull request against the default branch. When that happens the reviewer should change the base branch to the appropriate *Feature branch* instead. If the pull request does not fit in any *Feature branch*, the reviewer needs to make decision to either:
+
+* Decline the pull request because it is best contributed to Gitea
+* Create a new *Feature branch*
+
+Returning contributors can figure out which *Feature branch* to base their pull request on using the list of *Feature branches* found in CONTRIBUTING.md
+
+# Granularity
+
+*Feature branches* can contain a number of commits grouped together, for instance for branding the documentation, the landing page and the footer. It makes it convenient for people working on that topic to get the big picture without browsing multiple branches. Creating a new *Feature branch* for each individual commit, while possible, is likely to be difficult to work with.
+
+Observing the granularity of the existing *Feature branches* is the best way to figure out what works and what does not. It requires adjustments from time to time depending on the number of contributors and the complexity of the Forgejo codebase that sits on top of Gitea.