update for 1.2.3

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
doc/codecs: fix dangling reference to codec-options chapter
(cherry picked from commit b4bd21b7fe2ad8be59b16538448586814e5db65b)

Signed-off-by: Timothy Gu <timothygu99@gmail.com>

Conflicts:
	doc/codecs.texi
doc/texi2pod.pl: skip printing chapter names if they are disabled
(cherry picked from commit c838701ce4515bd51f7827be0b20f256ba5c69f3)

Signed-off-by: Timothy Gu <timothygu99@gmail.com>