fix mandoc warnings

- sort references in SEE ALSO section to section number, name.
- cols.1: proper order of sections.
- wrap lines to max 79 column length.

chgrp.1

@@ -21,8 +21,8 @@ flag is specified, this process is recursively applied to
 everything in
 .Ar file .
 .Sh SEE ALSO
-.Xr chown 1 ,
-.Xr chown 2 ,
 .Xr chmod 1 ,
+.Xr chown 1 ,
 .Xr chmod 2 ,
+.Xr chown 2 ,
 .Xr getgrnam 3