docs(getting-source-use-tag): get source via tag

Suggest that users cloning the git repository check out a git tag for
the most recent release, rather than run master.

The most recent release number is included in the list of versions to
bump.

Author: djmitche

docs/_includes/_get-the-source.rst

@@ -6,6 +6,9 @@ this documentation. Download an archive file from the `releases page`_, or use
 
     $ git clone https://github.com/deis/deis.git
     $ cd deis
+    $ git checkout v1.6.0
+
+Check out the latest Deis release, rather than using the default (master).
 
 If you contribute to Deis or build components locally, use ``go get`` instead to
 clone the source code into your `$GOPATH`_:

docs/contributing/releases.rst

@@ -43,6 +43,7 @@ Patch Release
         database/Dockerfile \
         deisctl/cmd/cmd.go \
         deisctl/deis-version \
+        docs/_includes/_get-the-source.rst \
         docs/installing_deis/install-deisctl.rst \
         docs/installing_deis/install-platform.rst \
         docs/managing_deis/upgrading-deis.rst \
@@ -93,6 +94,7 @@ Major or Minor Release
     $ ./contrib/bumpver/bumpver -f A.B.C A.B.D \
         README.md \
         contrib/coreos/user-data.example \
+        docs/_includes/_get-the-source.rst \
         docs/installing_deis/install-deisctl.rst \
         docs/installing_deis/install-platform.rst \
         docs/managing_deis/upgrading-deis.rst \
@@ -173,6 +175,7 @@ Patch Release
     ./contrib/bumpver/bumpver -f A.B.C A.B.D \
       README.md \
       contrib/coreos/user-data.example \
+      docs/_includes/_get-the-source.rst \
       docs/installing_deis/install-deisctl.rst \
       docs/installing_deis/install-platform.rst \
       docs/managing_deis/upgrading-deis.rst \