maint: Mention web site maintenance in README

Now that we have a website that accepts patches on the list, the
main project should make it easier to find information about that
process.
Signed-off-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>
Reviewed-by: NFam Zheng <famz@redhat.com>

README

@@ -68,6 +68,10 @@ the QEMU website
   https://qemu.org/Contribute/SubmitAPatch
   https://qemu.org/Contribute/TrivialPatches
 
+The QEMU website is also maintained under source control.
+
+  git clone git://git.qemu.org/qemu-web.git
+  https://www.qemu.org/2017/02/04/the-new-qemu-website-is-up/
 
 Bug reporting
 =============