Update master for stable/victoria

Add file to the reno documentation build to show release notes for
stable/victoria.

Use pbr instruction to increment the minor version number
automatically so that master versions are higher than the versions on
stable/victoria.

Change-Id: Iad61fa88f8afa7d5f39154b9466338b417bbf40a
Sem-Ver: feature

releasenotes/source/index.rst

@@ -8,6 +8,7 @@ Contents
    :maxdepth: 2
 
    unreleased
+   victoria
    ussuri
    train
    stein

releasenotes/source/victoria.rst

+=============================
+Victoria Series Release Notes
+=============================
+
+.. release-notes::
+   :branch: stable/victoria