Grammar: 'as to'->'as for'

Fixup migrate-incoming text as requested by Eric in:

 http://lists.nongnu.org/archive/html/qemu-devel/2015-03/msg03362.htmlSigned-off-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>

qmp-commands.hx

@@ -686,7 +686,7 @@ Notes:
 
 (1) QEMU must be started with -incoming defer to allow migrate-incoming to
     be used
-(2) The uri format is the same as to -incoming
+(2) The uri format is the same as for -incoming
 
 EQMP
     {