update helm dependency revisions and notes

Author: estroz

Gopkg.toml

@@ -36,6 +36,7 @@
 
 [[constraint]]
   name = "k8s.io/helm"
+  # Update to 2.12.0 when released.
   version = "=2.12.0-rc.1"
 
 [[constraint]]
@@ -48,7 +49,7 @@
 
 # We need overrides for the following imports because dep can't resolve them
 # correctly. The easiest way to get this right is to use the versions that
-# k8s.io/helm uses. See https://github.com/helm/helm/blob/v2.11.0/glide.lock
+# k8s.io/helm uses. See https://github.com/helm/helm/blob/v2.12.0-rc.1/glide.lock
 [[override]]
   name = "github.com/russross/blackfriday"
   revision = "300106c228d52c8941d4b3de6054a6062a86dda3"
@@ -59,4 +60,4 @@
 
 [[override]]
   name = "github.com/docker/docker"
-  revision = "4f3616fb1c112e206b88cb7a9922bf49067a7756"
+  revision = "a9fbbdc8dd8794b20af358382ab780559bca589d"