Documentation for Login-Time attribute needs improvement

[Trevor Warwick]

The documentation for the Login-Time attribute doesn't make it clear that
multiple time ranges are supported within a day.

For example this setting:

"Wk0900-1100,Wk1700-2100"

would allow access on weekdays in two defined time bands.

This was a capability that I'd wanted for a while, and only realised it was
possible after I read the code.  So I'd suggest that the following
documentation is updated to make it clear that this is supported:

https://networkradius.com/doc/3.0.10/raddb/mods-available/logintime.html

https://wiki.freeradius.org/config/Users