[PATCH] docs: Remove broken link to Xen channel doc

[Jim Fehlig]

Many of Xen's text documents have been converted to man pages over
the years, the channel doc being one of them. Replace the broken
channel.txt link with the name of the man page providing the same
information.

Signed-off-by: Jim Fehlig <jfehlig at suse.com>
---
 docs/formatdomain.rst | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst
index 0f78aa3a8c..aa7ea61258 100644
--- a/docs/formatdomain.rst
+++ b/docs/formatdomain.rst
@@ -6353,11 +6353,10 @@ types have different ``target`` attributes.
 ``xen``
    Paravirtualized Xen channel. Channel is exposed in the guest as a Xen console
    but identified with a name. Setup and consumption of a Xen channel depends on
-   software and configuration in the guest (for more info, please see
-   http://xenbits.xen.org/docs/unstable/misc/channel.txt). Channel source path
-   semantics are the same as the virtio target type. The ``state`` attribute is
-   not supported since Xen channels lack the necessary probing mechanism.
-   :since:`Since 2.3.0`
+   software and configuration in the guest. See the xen-pv-channel(7) man page
+   for more information. Channel source path semantics are the same as the virtio
+   target type. The ``state`` attribute is not supported since Xen channels lack
+   the necessary probing mechanism. :since:`Since 2.3.0`
 ``spicevmc``
    Paravirtualized SPICE channel. The domain must also have a SPICE server as a
    `graphics device <#elementsGraphics>`__, at which point the host piggy-backs
-- 
2.29.2