Add documentation on config mem.

Explain why "config mem" is required as it may not be very intuitive.

eem/tm_sw_autoconf.tcl

@@ -282,6 +282,10 @@ if { $config != {} || $image != {} } {
     }
 
     if { $config != {} } {
+	# XXX: This seems weird, but it's required to make sure the VLAN database
+	# is properly updated upon reboot.  By loading the startup config into
+	# running before rebooting, this reliable ensures the VLAN database is
+	# consistent.
         if { [catch {cli_exec $cli(fd) "config mem"} result] } {
             error $result $errorInfo
     	  }