Update TODO list.

doc/TODO

@@ -1,6 +1,6 @@
 TODO list for PostgreSQL
 ========================
-Last updated:		Tue Nov 27 16:22:52 EST 2001
+Last updated:		Wed Nov 28 00:44:46 EST 2001
 
 Current maintainer:	Bruce Momjian (pgman@candle.pha.pa.us)
 
@@ -179,6 +179,8 @@ COMMANDS
 	o ALTER TABLE ADD PRIMARY KEY (Christopher Kings-Lynne)
 	o ALTER TABLE ADD UNIQUE (Christopher Kings-Lynne)
 	o ALTER TABLE ADD COLUMN column SERIAL doesn't create sequence
+	o ALTER TABLE ADD COLUMN column SET DEFAULT should fill existing
+	  rows with DEFAULT value or allow NULLs in existing rows
 * CLUSTER
 	o cluster all tables at once
 	o prevent lose of indexes, permissions, inheritance (Bruce)