pgsql: Add: > o ARRAY[[1, 2], [3, 4]])[1] should return the same values as

Log Message:
-----------
Add:
> o ARRAY[[1,2],[3,4]])[1] should return the same values as
> ARRAY[[1,2],[3,4]])[1:1];
>

Modified Files:
--------------
pgsql/doc:
TODO (r1.2055 -> r1.2056)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/TODO.diff?r1=1.2055&r2=1.2056)
pgsql/doc/src/FAQ:
TODO.html (r1.556 -> r1.557)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/FAQ/TODO.html.diff?r1=1.556&r2=1.557)