Update Docs for DataSource password

[ibmbwolfe]

Is your feature request related to a problem? Please describe.
Yes, with the initial setup/configuration of the datasource in grafana.

Describe the solution you'd like
Update the documentation for the basic authentication to reference using the base64 encoded password for the datasource configuration

Describe alternatives you've considered
Reaching out to the documentation owner.

Additional context
Update the following link for the "Basic Authentication" to include using the base64 encode password over the un-encoded password for the datasource.
https://github.com/IBM/ibm-spectrum-scale-bridge-for-grafana/wiki/Setup-Grafana