maintaining: initial "Releasing" section

Author: MattSturgeon

MAINTAINING.md

@@ -5,3 +5,27 @@ This file is intended as a reference for Nixvim's core maintainers, although it
 ## Deprecation
 
 The deprecation policy discussion is happening in [#3181](https://github.com/nix-community/nixvim/issues/3181).
+
+## Releasing
+
+Nixvim releases stable versions in sync with nixpkgs. A YY.05 version is released in May and a YY.11 version is released in November.
+
+We do not need to wait for the release to be "stable" before creating a branch, however we _should_ wait before updating links and references on the `main` branch.
+
+Creating a stable branch may require temporarily disabling branch protection. This can only be done by an "admin" or "owner".
+
+Once a stable branch is created, its flake inputs should be updated to point to the corresponding stable versions.
+The branch can be created before these exist, in which case they should be updated when the corresponding stable inputs become available.
+
+Once a stable branch is created, it should be added to the `update-other` workflow on the `main` branch.
+
+Once a stable branch is considered "public", it should be added to the `build_documentation` workflow on the `main` branch.
+This can be done while the version is still "beta".
+
+Once a stable version is considered "out of beta", references to Nixvim's stable branch should be updated on the `main` branch to reference the new version.
+
+### Deprecating old releases
+
+Once a stable branch is deprecated, it should be removed from the `update-other` workflow on the `main` branch.
+
+It should also be removed from the `build_documentation` workflow on the `main` branch.