Merge pull request #13648 from rgacogne/ddist-doh3doc

dnsdist: Document `showDOH3Frontends`, how to advertise HTTP/3 support over HTTP/2

diff --cc pdns/dnsdistdist/docs/guides/dns-over-http3.rst
Simple merge

diff --cc pdns/dnsdistdist/docs/reference/config.rst
index 11a39ff6aaea47ee31d8cadbb178fe1653820f5e,d5d9004d1ef997c89008c373e30927895a73b81f..2e15ebd8fc0367a51ab8c72f3d237260d9a05b96
--- 1/pdns/dnsdistdist/docs/reference/config.rst
--- 2/pdns/dnsdistdist/docs/reference/config.rst
+++ b/pdns/dnsdistdist/docs/reference/config.rst
@@@ -181,9 -182,10 +182,10 @@@ Listen Socket
    .. versionadded:: 1.9.0
  
    Listen on the specified address and UDP port for incoming DNS over HTTP3 connections, presenting the specified X.509 certificate.
+   More information is available in :doc:`../guides/dns-over-http3`.
  
    :param str address: The IP Address with an optional port to listen on.
 -                      The default port is 853.
 +                      The default port is 443.
    :param str certFile(s): The path to a X.509 certificate file in PEM format, a list of paths to such files, or a TLSCertificate object.
    :param str keyFile(s): The path to the private key file corresponding to the certificate, or a list of paths to such files, whose order should match the certFile(s) ones. Ignored if ``certFile`` contains TLSCertificate objects.
    :param table options: A table with key: value pairs with listen options.