DOCS-1063 version numbers

Author: Bob Grabar

source/release-notes.txt

@@ -3,8 +3,9 @@
 Release Notes
 -------------
 
-Always install the latest, stable version of MongoDB. See the
-following release notes for an account of the changes in major
+Always install the latest, stable version of MongoDB. See :ref:`release-version-numbers`.
+
+See the following release notes for an account of the changes in major
 versions. Release notes also include instructions for upgrade.
 
 Current stable release (v2.2-series):
@@ -40,3 +41,43 @@ Other MongoDB release notes:
    :maxdepth: 2
 
    /release-notes/drivers-write-concern
+
+.. _release-version-numbers:
+
+Version Numbers
+~~~~~~~~~~~~~~~
+
+There are three numbers in a MongoDB version:
+
+``<major version number>.<release number>.<revision number>``
+
+The second number, the release number, indicates release stability. An
+odd release number indicates the release is still in
+development. An even release number indicates a general availability release.
+
+Additionally, the three numbers indicate the following:
+
+- ``<major version number>``: This rarely changes. A change to this number
+  indicates very large changes to MongoDB.
+
+- ``<release number>``: A release can include many changes, including new
+  features and updates. Some changes could possibly break backwards
+  compatibility, which would be noted in the Release Notes.
+  Even-numbered release numbers are stable branches. Odd-numbered
+  release numbers are development branches.
+
+- ``<revision number>``: This is used for changes pertaining to bugs and
+  security issues.
+
+Example Version Numbers
+```````````````````````
+
+- 1.0.0 : First GA release
+
+- 1.0.x : Bug fixes to 1.0.x. It is highly recommended to upgrade, very
+  little risk.
+
+- 1.1.x : Development release. Includes new features not fully finished
+  and other works-in-progress. Some things may be different than 1.0
+
+- 1.2.x : Second GA release. This is a culmination of the 1.1.x release.