pgsql: Add mention of possible patent problems with star joins, per

Log Message:
-----------
Add mention of possible patent problems with star joins, per Joshua
Drake:

< and merge the bitmaps to perform the join on the fact table.

and merge the bitmaps to perform the join on the fact table. Some
of these algorithms might be patented.

Modified Files:
--------------
pgsql/doc:
TODO (r1.1731 -> r1.1732)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/TODO.diff?r1=1.1731&amp;r2=1.1732)
pgsql/doc/src/FAQ:
TODO.html (r1.236 -> r1.237)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/FAQ/TODO.html.diff?r1=1.236&amp;r2=1.237)