db.execute: fix duplicated word in in docs (#3370)

db/db.execute/db.execute.html

@@ -12,7 +12,7 @@ <h2>NOTES</h2>
 <em><a href="db.connect.html">db.connect</a></em>, they are taken as default
 values and do not need to be specified each time.
 <p>
-If you have a large number of SQL commands to process, it is much much
+If you have a large number of SQL commands to process, it is much
 faster to place all the SQL statements into a text file and
 use <b>input</b> file parameter than it is to process each statement
 individually in a loop. If multiple instruction lines are given, each