docs(install/upgrade): highlight that deisctl must match Deis' version

Author: mboersma

docs/installing_deis/install-deisctl.rst

@@ -39,8 +39,10 @@ To change installation options, save the installer directly:
 Then run the downloaded file as a shell script. Append ``--help`` to see what options
 are available.
 
-If you are using a specific Deis release (not latest), you'll want to use the deisctl built for
-your release.
+.. important::
+
+    Always use a version of ``deisctl`` that matches the Deis release.
+    Verify this with ``deisctl --version``.
 
 Builds are hosted on an S3 bucket at this URL format:
 

docs/managing_deis/upgrading-deis.rst

@@ -20,6 +20,11 @@ leaving your applications and platform data intact.  This is the easiest and lea
 The general approach is to use ``deisctl`` to uninstall all platform components, update the platform version
 and then reinstall platform components.
 
+.. important::
+
+    Always use a version of ``deisctl`` that matches the Deis release.
+    Verify this with ``deisctl --version``.
+
 .. note::
 
     In-place upgrades are supported starting from Deis version 0.14.0