Remove temporary table from comment.install

To continue the quote from MySQL manual

In this case, MySQL creates a temporary table to hold the rows from the SELECT and then inserts those rows into the target table.

I just tested that INSERT...SELECT works into the same table with just INSERT and SELECT grants. So while the manual says there is a temporary table being made that's behind the scenes, somewhat similar to the well known fact that some ordinary SELECTs result in a temporary table (and when those get on disk, your performance plumets).

Me.

test=# create table boo (foo int);
CREATE TABLE
test=# insert into boo values (1);
INSERT 0 1
test=# insert into boo values (2);
INSERT 0 1
test=# insert into boo select * from boo;
INSERT 0 2
test=# select * from boo;
 foo
-----
   1
   2
   1
   2
(4 rows)