main/apcupsd: manify with mandoc

`col` is unavailable as it has been disabled since
https://github.com/util-linux/util-linux/commit/8886d84e25a457702b45194d69a47313f76dc6bc

as far as i can tell, these files are not installed in
the .apk, as besides `doc/Makefile`, `*.man.txt` is only
mentioned in `platforms/mingw/installer/winapcupsd.nsi`,
so it doesn't matter what output is produced by mandoc.

also, add `mandoc` to `makedepends` and sort that alphabetically