Remove 'Unmaintained' phase

During Xena Virtual PTG on the Technical Committee session there was a
discussion, that the 'Unmaintained' phase is not really clear for the
community and just creates confusion. The decision was to simply remove
this phase as the process is more clear and works well without it.

Change-Id: I9589cbdd74d83d23ad42ce6724e3b8e4cc56c44d

doc/source/stable-branches.rst

@@ -29,10 +29,6 @@ Project stable branches will be in one of the following states:
      * While there are community members maintaining it.
      * All bugfixes (that meet the criteria described below) are
        appropriate.  No Releases produced, reduced CI commitment.
-   - * Unmaintained
-     * 0 - 6 months
-     * The branch is under Extended Maintenance rules, but there are no
-       maintainers.
    - * End of Life (EOL)
      * N/A
      * Branch no longer accepting changes.
@@ -114,26 +110,14 @@ of Life`_ below.
    <https://governance.openstack.org/tc/resolutions/20180301-stable-branch-eol.html>`_.
 
 
-.. _`Unmaintained`:
-
-Unmaintained
-------------
-
-At this stage of the project/branch the Extended Maintenance policy applies but
-CI may not be working and/or there aren't any active maintainers.  Projects
-that remain in this state for 6 months will be transitioned to `End of Life`_.
-Should  maintainers be found a project can be placed back into Extended
-Maintenance.
-
 .. _End Of Life:
 
 End of Life
 -----------
 
-After a project/branch exceeds the time allocation as `Unmaintained`_, or a
-team decides to explicitly end support for a branch, it
-will become End of Life.  The HEAD of the appropriate branch will be tagged
-as ``$series-eol`` and the branch deleted.
+After a project/branch becomes unmaintained or a team decides to explicitly end
+support for a branch, it will become End of Life. The HEAD of the appropriate
+branch will be tagged as ``$series-eol`` and the branch deleted.
 
 To initiate this transition, either the PTL of the given project or other
 stable maintainer should: