VOL-630 - update documentation with default creds and doc ssh key support

Change-Id: I96ec086f55d7861068ee59eb63fef7ff79472100
diff --git a/compose/voltha-stack.yml.j2 b/compose/voltha-stack.yml.j2
index f8f536f..330131e 100644
--- a/compose/voltha-stack.yml.j2
+++ b/compose/voltha-stack.yml.j2
@@ -412,7 +412,7 @@
   # The CLI container provides an CLI to the VOLTHA capabilitiy 
   # that can be accessed via SSH.
   cli:
-    image: "${REGISTRY}${REPOSITORY}voltha-cli:${TAG:-latest}"
+    image: "${REGISTRY}${REPOSITORY}voltha-cli${CUSTOM_CLI_LABEL}:${TAG:-latest}"
     logging:
       driver: "json-file"
       options: