Update Docs and Comments for Grafana Password

General MR

Summary

The current doc incorrectly instructs users to change Grafana password through the monitoring.values.grafana.adminPassword values when it should be changes through grafana.values.adminPassword.

Relevant logs/screenshots

(Include any relevant logs/screenshots)

Linked Issue

Links to https://repo1.dso.mil/big-bang/product/packages/monitoring/-/issues/243

Upgrade Notices

N/A

Closes #243