Add help next to White/Admin list to explain the format

[bocekm]

Please add the help message next to the White list and Admin list to tell what is the allowed separator between github nicknames. I've tried one nickname on one line (separated by new line) but it doesn't seem to work. Anyway the help message would alleviate me and other users from guesswork.

[grahamwhaley]

and over a year later..... @bocekm - did you ever work out the rules? If so, post them here so at least if they never make it into the code base as least somebody might find this PR as a reference :-)

[grahamwhaley]

OK, for some sort of ref then.... When I had fred mary in the box, it did not complain. When I changed that to fred, mary, I got the following text show below the box in red from the validation check...

GitHub username may only contain alphanumeric characters or dashes and cannot have multiple consecutive dashes and cannot begin or end with a dash. Separate them with whitespaces.

[dutor]

For other guys information, the white list is separated by whitespaces.