[2.2] Consolidate conf file help text with man pages

[rdmark]

netatalk2 has the bad habit of documenting configuration options in both the conf files themselves and in the man pages. It's ideal to have just one source of truth, I think. Right now there are discrepancies between the two, plus the ongoing overhead of having to edit both when you make updates...

[rdmark]

I propose removing all the help text in conf files, and folding it into the man pages.

[rdmark]

PR ready that does this for afpd.conf and AppleVolumes.default.conf; the other files don't need immediate attention I think.

I also touched up the related man pages for those two files as I went through and checked that all conf file documentation is reflected in the man pages. I only found one that wasn't: illegalseq in AppleVolumes. I'll do some research to understand if it is a deprecated option or a gap in documentation.

[rdmark]

Turns out the illegalseq option was added in 2.0.4 but never documented in the AppleVolumes man page, only the conf file. Pushed a commit to add documentation.