Improve documentation for access list

[robogeek]

Is your feature request related to a problem? Please describe.

In the UI for the Access List dialog, for the Access pane, there's no guidance. The help popup for the Access List tab does not describe the format of an entry for the Access pane.

This is all which is said:

Access Lists provide a blacklist or whitelist of specific client IP addresses along with authentication for the Proxy Hosts via Basic HTTP Authentication.

Nowhere does it describe the entry format that is allowed.

Describe the solution you'd like

Improve the description. For example - if it takes a CIDR then say so, and give a couple CIDR examples.

Describe alternatives you've considered

n/a

Additional context

The only way I could learn how this works is from another bug report: #763