doc/rados: remove dual-stack docs

Remove references to dual-stack mode in
doc/rados/configuration/network-config-ref.rst and
doc/rados/configuration/msgr2.rst. This feature seems to have been
planned but never to have been completely implemented.

See the tracker issue listed below for an email exchange detailing the
confusion caused by the presence in the documentation of this
now-removed information.

Fixes: https://tracker.ceph.com/issues/65631

Signed-off-by: Zac Dover <[email protected]>

Author: zdover23

doc/rados/configuration/msgr2.rst

@@ -90,10 +90,6 @@ Similarly, two options control whether IPv4 and IPv6 addresses are used:
   * :confval:`ms_bind_ipv6` [default: false] controls whether a daemon binds
     to an IPv6 address
 
-.. note:: The ability to bind to multiple ports has paved the way for
-   dual-stack IPv4 and IPv6 support.  That said, dual-stack operation is
-   not yet supported as of Quincy v17.2.0.
-
 Connection modes
 ----------------
 

doc/rados/configuration/network-config-ref.rst

@@ -214,28 +214,6 @@ following option to the ``[global]`` section of your Ceph configuration file.
 We prefer that the cluster network is **NOT** reachable from the public network
 or the Internet for added security.
 
-IPv4/IPv6 Dual Stack Mode
--------------------------
-
-If you want to run in an IPv4/IPv6 dual stack mode and want to define your public and/or
-cluster networks, then you need to specify both your IPv4 and IPv6 networks for each:
-
-.. code-block:: ini
-
-	[global]
-		# ... elided configuration
-		public_network = {IPv4 public-network/netmask}, {IPv6 public-network/netmask}
-
-This is so that Ceph can find a valid IP address for both address families.
-
-If you want just an IPv4 or an IPv6 stack environment, then make sure you set the `ms bind`
-options correctly.
-
-.. note::
-   Binding to IPv4 is enabled by default, so if you just add the option to bind to IPv6
-   you'll actually put yourself into dual stack mode. If you want just IPv6, then disable IPv4 and
-   enable IPv6. See `Bind`_ below.
-
 Ceph Daemons
 ============