add rhel TAM info

docs/onboarding/index.md

@@ -115,6 +115,13 @@ pts adduser -user $USERNAME -group linux:adm
 3. commit and push
 4. ``ssh build@lxsoftadm01`` then ``cd lxdist-build`` then ``git pull origin master``
 
+### External accounts
+
+Ask a current member of the Linux team to add you to:
+
+- access.redhat.com
+- hub.docker.com
+
 ### Common agreements
 
 TBD, but: