x86: fix documentation bug about relocatability

This patch fixes a small bug in documentation: x86_64 also has now
the ability to build a relocatable kernel.
Signed-off-by: Bernhard Walle <bwalle@suse.de>
Cc: vgoyal@redhat.com
Cc: kexec@lists.infradead.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Documentation/kdump/kdump.txt

@@ -109,7 +109,7 @@ There are two possible methods of using Kdump.
 2) Or use the system kernel binary itself as dump-capture kernel and there is
    no need to build a separate dump-capture kernel. This is possible
    only with the architecutres which support a relocatable kernel. As
-   of today i386 and ia64 architectures support relocatable kernel.
+   of today, i386, x86_64 and ia64 architectures support relocatable kernel.
 
 Building a relocatable kernel is advantageous from the point of view that
 one does not have to build a second kernel for capturing the dump. But