[PATCH] docs: Tweak location of qemu nbd extensions

[Eric Blake <eblake@redhat.com>]

Upstream QEMU is moving the location of its NBD docs, as of its commit
XXXX[1].  Instead of pointing to the raw git source file, point to the
rendered html version built from rST.

CC: qemu-devel@nongnu.org
Signed-off-by: Eric Blake <eblake@redhat.com>

---

[1] Commit id TBD, I will update this patch to match reality once
qemu's patch lands, and only push this once the new link actually
exists.  See also
https://lists.gnu.org/archive/html/qemu-devel/2024-08/msg00223.html

---
 doc/proto.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/proto.md b/doc/proto.md
index cf1f60f..565fbeb 100644
--- a/doc/proto.md
+++ b/doc/proto.md
@@ -963,7 +963,7 @@ Namespaces MUST be consist of one of the following:
 Third-party implementations can register additional namespaces by
 simple request to the mailing-list. The following additional
 third-party namespaces are currently registered:
-* `qemu`, maintained by [qemu.org](https://gitlab.com/qemu-project/qemu/-/blob/master/docs/interop/nbd.txt)
+* `qemu`, maintained by [qemu.org](https://www.qemu.org/docs/master/interop/nbd.html)

 Save in respect of the `base:` namespace described below, this specification
 requires no specific semantics of metadata contexts, except that all the
-- 
2.45.2