Document new variables.
* man/newusers.8.xml, man/login.defs.5.xml,
man/login.defs.d/GID_MAX.xml, man/login.defs.d/UID_MAX.xml:
newusers uses now the GID_MAX, GID_MIN, UID_MAX, UID_MIN,
SYS_GID_MAX, SYS_GID_MIN, SYS_UID_MAX, and SYS_UID_MIN variables.
* man/groupadd.8.xml, man/login.defs.5.xml: groupadd uses now the
SYS_GID_MAX, and SYS_GID_MIN variables.
* man/login.defs.5.xml: useradd uses now the SYS_GID_MAX,
SYS_GID_MIN, SYS_UID_MAX, and SYS_UID_MIN variables.
and /etc/passwd to section FILES.
* man/newusers.8.xml: Mentions that PAM is not used to set the
passwords.
* man/chpasswd.8.xml: Added section FILES (/etc/passwd,
/etc/shadow, /etc/login.defs).
* man/chpasswd.8.xml: Use the same paragraph as in newusers.8.xml
to indicate that PAM is not used.
* man/chgpasswd.8.xml: Added section FILES (/etc/group,
/etc/gshadow, /etc/login.defs).