[libvirt] [PATCH] docs: document rng backend path restrictions of older libvirt

[Ján Tomko]

Commit 67f2b72 removed the path restrictions for rng backend,
along with the documentation of the restriction.

Restore the documentation for users still using older libvirt.

https://bugzilla.redhat.com/show_bug.cgi?id=1074464
---
 docs/formatdomain.html.in | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
index daa0891..17e563c 100644
--- a/docs/formatdomain.html.in
+++ b/docs/formatdomain.html.in
@@ -6356,9 +6356,10 @@ qemu-kvm -net nic,model=? /dev/null
             <p>
               This backend type expects a non-blocking character device as
               input. The file name is specified as contents of the
-              <code>backend</code> element. When no file name is specified
-              the hypervisor default is used. For qemu, the default is
-              /dev/random
+              <code>backend</code> element. <span class='since'>Since 1.3.4</span>
+              any path is accepted. Before that /dev/random and /dev/hwrng were
+              the only accepted paths. When no file name is specified the hypervisor
+              default is used. For qemu, the default is /dev/random
             </p>
           </dd>
           <dt><code>egd</code></dt>
-- 
2.7.3