correct the mark for urxvt mouse (vim)

vim-various-mark.diff

diff -r 11d40fc82f11 runtime/doc/various.txt
--- a/runtime/doc/various.txt	Thu Jul 12 22:01:11 2012 +0200
+++ b/runtime/doc/various.txt	Sat Jul 21 19:04:44 2012 +0900
@@ -355,7 +355,7 @@
 B  *+mouse_netterm*	Unix only: netterm mouse handling |netterm-mouse|
 N  *+mouse_pterm*		QNX only: pterm mouse handling |qnx-terminal|
 N  *+mouse_sysmouse*	Unix only: *BSD console mouse handling |sysmouse|
-N  *+mouse_urxvt*		Unix only: urxvt mouse handling |urxvt-mouse|
+B  *+mouse_urxvt*		Unix only: urxvt mouse handling |urxvt-mouse|
 N  *+mouse_xterm*		Unix only: xterm mouse handling |xterm-mouse|
 B  *+multi_byte*		16 and 32 bit characters |multibyte|
    *+multi_byte_ime*	Win32 input method for multibyte chars |multibyte-ime|