qemu-options: Fix broken sheepdog URL

The sheepdog URL is broken twice: First it uses a duplicated
http:// prefix, second the website seems to have moved to
https://sheepdog.github.io/sheepdog/ instead.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Jeff Cody <jcody@redhat.com>
diff --git a/qemu-options.hx b/qemu-options.hx
index 1e815ef..9936cf3 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2586,7 +2586,7 @@
 qemu-system-i386 --drive file=sheepdog://192.0.2.1:30000/MyVirtualMachine
 @end example
 
-See also @url{http://http://www.osrg.net/sheepdog/}.
+See also @url{https://sheepdog.github.io/sheepdog/}.
 
 @item GlusterFS
 GlusterFS is a user space distributed file system.