documentation change request: nogroup and HP-UX

[V. T. Mueller]

Hello,

on HP-UX (tested 11.23, checked 11.11) there is:
nogroup:*:-2:
Which leads to a rsync daemon that will fail upon connect:

[..]
chdir("/") ............................................... = 0
setgid(-2) ............................................... ERR#22 EINVAL
open("/usr/lib/nls/msg/C/strerror.cat", O_RDONLY, 032630)  ERR#2 ENOENT
open("/usr/lib/nls/C///strerror.cat", O_RDONLY, 032630) .. ERR#2 ENOENT
time(NULL) ............................................... = 1130323189
getpid() ................................................. = 20543 
(20542)
brk(0x40018000) .......................................... = 0
ioctl(5, TCGETA, 0x7f7f32b8) ............................. ERR#25 ENOTTY
write(5, "2 0 0 5 / 1 0 / 2 6   1 2 : 3 9 ".., 75) ....... = 75
select(5, NULL, 0x7f7f2520, NULL, 0x7f7f2730) ............ = 1
write(4, "@ E R R O R :   s e t g i d   f ".., 22) ....... = 22
exit(255) ................................................ 
WIFEXITED(255)

So I think there should be a hint in the README file stating that 
building on HP-UX requires a "nobody" group with a postive gid to be 
created in order to get a usable binary (tested & working).

Cheers,
vt