Add documentation about release versioning and process

docs/source/internal/index.rst

@@ -17,6 +17,7 @@ pull gently.
 
     contributing
     writing-documentation
+    releases
     checker
     cli
     formatters

docs/source/internal/releases.rst

@@ -0,0 +1,43 @@
+==================
+ Releasing Flake8
+==================
+
+There is not much that is hard to find about how |Flake8| is released.
+
+- We use **major** releases (e.g., 2.0.0, 3.0.0, etc.) for big releases (e.g.,
+  large scale refactors). This can also contain dependency version changes.
+
+- We use **minor** releases (e.g., 2.1.0, 2.2.0, 3.1.0, 3.2.0, etc.) for
+  releases that contain features and dependency version changes.
+
+- We use **patch** releases (e.g., 2.1.1, 2.1.2, 3.0.1, 3.0.10, etc.) for
+  releases that contain *only* bug fixes. These *never* contain changes to
+  dependency version constraints.
+
+
+Process
+=======
+
+To prepare a release, we create a file in :file:`docs/source/releases/` named:
+``{{ release_number }}.rst`` (e.g., ``3.0.0.rst``). We note bug fixes,
+improvements, and dependency version changes as well as other items of note
+for users.
+
+Before releasing, the following tox test environments must pass:
+
+- Python 2.7 (a.k.a., ``tox -e py27``)
+
+- Python 3.4 (a.k.a., ``tox -e py34``)
+
+- Python 3.5 (a.k.a., ``tox -e py35``)
+
+- PyPy (a.k.a., ``tox -e pypy``)
+
+- Linters (a.k.a., ``tox -e linters``)
+
+We tag the most recent commit that passes those items and contains our release
+notes.
+
+Finally, we run ``tox -e release`` to build source distributions (e.g., 
+``flake8-3.0.0.tar.gz``), universal wheels, and upload them to PyPI with
+Twine.