Update bitmap index description:

<   Such indexes could be more compact if there are only a few unique values.
>   Such indexes could be more compact if there are only a few distinct values.
>   Such indexes can also be compressed.  Keeping such indexes updated can be
>   costly.

doc/TODO

@@ -6,7 +6,7 @@ TODO list for PostgreSQL
 Bracketed items "[]" have more detail.
 
 Current maintainer:	Bruce Momjian (pgman@candle.pha.pa.us)
-Last updated:		Mon Nov  8 23:13:58 EST 2004
+Last updated:		Tue Nov  9 10:10:57 EST 2004
 
 The most recent version of this document can be viewed at the PostgreSQL web
 site, http://www.PostgreSQL.org.
@@ -261,7 +261,9 @@ Indexes
 * Allow the creation of on-disk bitmap indexes which can be quickly
   combined with other bitmap indexes
 
-  Such indexes could be more compact if there are only a few unique values.
+  Such indexes could be more compact if there are only a few distinct values.
+  Such indexes can also be compressed.  Keeping such indexes updated can be
+  costly.
 
 * Allow use of indexes to search for NULLs