Fix typo in dbcachenowsync description.

doc/man/man5/slapd.conf.5

@@ -269,7 +269,7 @@ method, this option is ignored without comment.  The default is 100000 bytes.
 .TP
 .B dbcachenowsync
 Specify that database writes should not be immediately synchronized
-with in memory changes.  Enabling this option may improving performance
+with in memory changes.  Enabling this option may improve performance
 at the expense of data security.
 .TP
 .B directory <directory>