Add a button similar to help, link directive related documents

[rabbit008]

What would you like to be added:Add a button similar to help, link directive related documents

Why is this needed:Some users may not be familiar with nnictl-command,so it would be more friendly if there have a quick view link.

Without this feature, how does current nni work: normally

Components that may involve changes: A help button

Brief description of your proposal if any:as above

[rabbit008]

A icon link to https://nni.readthedocs.io/en/latest/Tutorial/WebUI.html

[lvybriage]

this issue needs design to estimate.