pgsql: Update TODO: < o Consider reducing on-disk varlena length from

Log Message:
-----------
Update TODO:

< o Consider reducing on-disk varlena length from four to two
< because a heap row cannot be more than 64k in length

o Consider reducing on-disk varlena length from four bytes to
two because a heap row cannot be more than 64k in length

Modified Files:
--------------
pgsql/doc:
TODO (r1.2166 -> r1.2167)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/TODO.diff?r1=1.2166&amp;r2=1.2167)
pgsql/doc/src/FAQ:
TODO.html (r1.667 -> r1.668)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/FAQ/TODO.html.diff?r1=1.667&amp;r2=1.668)