Add more detail about types of releases

docs/source/internal/releases.rst

@@ -4,15 +4,71 @@
 
 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.,
+- We use **major** releases (e.g., 2.0.0, 3.0.0, etc.) for big, potentially
-  large scale refactors). This can also contain dependency version changes.
+  backwards incompatible, releases.
 
 - 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
+  releases that contain *only* bug fixes.
-  dependency version constraints.
+
+In this sense we follow semantic versioning. But we follow it as more of a set
+of guidelines. We're also not perfect, so we may make mistakes, and that's
+fine.
+
+
+Major Releases
+==============
+
+Major releases are often associated with backwards incompatibility. |Flake8|
+hopes to avoid those, but will occasionally need them.
+
+Historically, |Flake8| has generated major releases for:
+
+- Unvendoring dependencies (2.0)
+
+- Large scale refactoring (2.0, 3.0)
+
+- Subtly breaking CLI changes (3.0)
+
+- Breaking changes to its plugin interface (3.0)
+
+Major releases can also contain:
+
+- Bug fixes (which may have backwards incompatible solutions)
+
+- New features
+
+- Dependency changes
+
+
+Minor Releases
+==============
+
+Minor releases often have new features in them, which we define roughly as:
+
+- New command-line flags
+
+- New behaviour that does not break backwards compatibility
+
+- New errors detected by dependencies, e.g., by raising the upper limit on
+  PyFlakes we introduce F405
+
+- Bug fixes
+
+
+Patch Releases
+==============
+
+Patch releases should only ever have bug fixes in them.
+
+We do not update dependency constraints in patch releases. If you do not
+install |Flake8| from PyPI, there is a chance that your packager is using
+different requirements. Some downstream redistributors have been known to
+force a new version of PyFlakes, pep8/PyCodestyle, or McCabe into place.
+Occasionally this will cause breakage when using |Flake8|. There is little
+we can do to help you in those cases.
 
 
 Process