Update invocation documentation.

Update invocation documentation.

* doc/autoconf.texi (autoscan Invocation): Mention --debug.
(autoreconf Invocation): Mention -v.
(autom4te Invocation): Tie --freeze to -F, not -f.
(autoupdate Invocation): Mention --prepend-include.
* doc/install.texi (configure Invocation): Mention --help=short,
--help=recursive, -n/--no-create, --prefix.  Avoid TABs.
* bin/autoscan.in ($help): Omit space before `...'.
* bin/ifnames.in ($help): Likewise.
* bin/autoconf.as (Usage): Likewise.
* bin/autoreconf.in ($help): Likewise.
* bin/autoheader.in ($help): Likewise.
* bin/autom4te.in ($help): Likewise.
* bin/autoupdate.in ($help): Likewise.
* lib/autoconf/status.m4 (_AC_OUTPUT_CONFIG_STATUS): Use
`[OPTION]...', rather than `[OPTIONS]'.  Mention --silent.  Indent
--file correctly.

Signed-off-by: Eric Blake <ebb9@byu.net>