feat(dev): add release and versioning guidelines

Signed-off-by: Jose Martins <[email protected]>

source/development/versioning.rst

@@ -1,4 +1,67 @@
 .. _versioning:
 
-Versioning
-==========
+Releases and Versioning
+======================
+
+Bao Project's repos follow a `semantic versioning scheme <https://semver.org/>`_ where, for each
+release, the specific `git commit is tagged <https://git-scm.com/book/en/v2/Git-Basics-Tagging>`
+with  a label with the form MAJOR.MINOR.PATCH, where each version component is incremented as
+following:
+
+* **MAJOR** version when you make incompatible API changes
+* **MINOR** version when you add functionality in a backward compatible manner
+* **PATCH** version when you make backward compatible bug fixes
+
+When incrementing a given version, the lower order components must be set to 0.
+
+To illustrate, a project in its `2.3.1` version might:
+
+* bump to `2.3.2` if a given bug is patched;
+* go to `2.4.0` when adding new features that don't break interface compatibility;
+* tag `3.0.0` when adding new features that break interface compatibility;
+
+Release Cycle
+-------------
+
+Bao's Project releases follow a loosely time-based cycle. The expected release cadence,
+specifically, bumping the **MINOR** or **MAJOR** versions, is expected to be every 4 to 8 months,
+depending on the number of contributions on that given period. That is, if the number of
+contributions does not justify a release bump, the release can be postponed to a maximum of 8
+months.
+
+Each release cycle is essentially composed by two stages:
+
+* the **development stage**, where the normal development process goes on, PRs with either new
+  features, fixes or other are submitted, reviewed and merged asynchronously, following the
+  :ref:`contribution guidelines <contributing>`. 
+
+* during **stabilization stage**, the contributions made during the development stage should be
+  thorougly tested with the most comprehensive test batteries available. Further, integration tests
+  may be added at this point. Besides new tests, maintainers must stop accepting PRs that are not
+  bug fixes or documentation. This stage is expected to last between 2 to 8 weeks, so maintainers
+  should be aware to stop the development stage after a maximum of about 6 months depending on the
+  ammount of new contributions. More contributions will require a longer pre-release stage.
+
+At the end of the release cycle the version is tagged and the process starts all over again.s
+
+At any point during the release cycle **PATCH** version increments can be tagged to fix bugs,
+especially safety hazards or security vulnerabilities.
+
+
+Release Manager
+---------------
+
+For each release cycle one of the repo's maintainers (ideally always the same), should be elected
+the **release manager**, which will be responsible for:
+
+* deciding when the stabilization stage begins and ends;
+* coordinating other maintainers during the stabilization phase;
+* tagging and pushing the version to the repo;
+
+
+Submodule Management
+--------------------
+
+Upon a release tagging, each submodule in the repo should be pointing to a specific release of the
+submodule's repo. This may require that a repository's release cycle to be somewhat synchronized to
+the release cycle of its submodule dependencies.