Update the Helm and Tiller command docs
What does this Merge Request do?
Updates the docs with local Tiller commands, since GitLab no longer installs a remote Tiller server. See gitlab#209736 (closed)
Merge Request checklist
- [-] Tests added for new functionality. If not, please raise Issue to follow-up.
 - 
This change is backward compatible. If not, please include steps to communicate to our users.  - 
Documentation added/updated, if needed.  - [-] 
gdk doctortest added, if needed.