kexec: update URL of kexec homepage

The referenced html file does not exist anymore. Replace the URL with
the current project homepage.
Signed-off-by: NOlaf Hering <olaf@aepfle.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Documentation/kdump/kdump.txt

@@ -86,7 +86,7 @@ There is also a gitweb interface available at
 http://www.kernel.org/git/?p=utils/kernel/kexec/kexec-tools.git
 
 More information about kexec-tools can be found at
-http://www.kernel.org/pub/linux/utils/kernel/kexec/README.html
+http://horms.net/projects/kexec/
 
 3) Unpack the tarball with the tar command, as follows: