doc/x86: fix doc subdirs

The Documentation/i386 and Documentation/x86_64 directories and their
contents have been moved into Documentation/x86. Fix references to
those files accordingly.

Signed-off-by: Uwe Hermann <uwe@hermann-uwe.de>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index 7228369..da86fd5 100644
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -402,7 +402,7 @@
 	void *p = from_guest_phys(0x100000);
 
 	/* Go back to the start of the file and read the header.  It should be
-	 * a Linux boot header (see Documentation/i386/boot.txt) */
+	 * a Linux boot header (see Documentation/x86/i386/boot.txt) */
 	lseek(fd, 0, SEEK_SET);
 	read(fd, &boot, sizeof(boot));