Grafana - Githubissues

Improve the Grafana documentation and error handling

Improve the documentation for Configure Grafana to be better organized, to have links between sections.
Add a link to the grafana documentation from the error message for the "Add Grafana Host" view - if username/password validation fails persistently, direct the user to the help docs to set up an API token.

Put an x in the boxes that apply

[ ] Feature (non-breaking change which adds functionality)
[ ] Bug Fix (non-breaking change that fixes an issue)
[ ] Breaking Change (feature/fix that causes existing features to not work as expected)
[x] Documentation

[x] I have read the [contribute]contributing doc
[x] Classes, scripts, and environment variables follow existing naming convention
[x] Lint and Unit tests pass locally
[x] New features on hardware have been tested on a local Raspberry Pi
[x] Mention new programs/binaries if any must be installed along with this change
[x] Mention new environment variables if any have been added to hardware/env file
[x] Please make sure test coverage does not drop. If it does, please explain the reasons.
[x] Any new required python modules are added to the requirements.txt