Revert "DOCS-20573 arbiters write concern (#482) (#552)" (#554)

This reverts commit 96ed6dd.

Author: jason-price-mongodb

source/includes/admonition-multiple-arbiters.rst

@@ -1,21 +1,6 @@
 .. warning:: 
 
-   Avoid deploying more than one :term:`arbiter` in a :term:`replica
-   set`. See :ref:`rollbacks-multi-arbiters`.
+   Avoid deploying more than one arbiter per replica set.
 
-To add an arbiter to an existing replica set:
+   See also: :ref:`rollbacks-multi-arbiters`
 
-- Typically, if there are two or fewer data-bearing members in the
-  replica set, you might need to first set the :ref:`cluster wide write
-  concern <set_global_default_write_concern>` for the replica set.
-
-- See :ref:`cluster wide write concern
-  <set_global_default_write_concern>` for more information on why you
-  might need to set the cluster wide write concern.
-
-You do not need to change the cluster wide write concern before starting
-a new replica set with an arbiter.
-
-.. seealso::
-
-   :ref:`Default write concern formula <default-wc-formula>`

source/reference/write-concern.txt

@@ -468,8 +468,6 @@ For example, consider:
      topology that does not require all data bearing voting members to be
      available (e.g. P-S-S).
 
-.. include:: /includes/admonition-multiple-arbiters.rst
-
 Write Concern Provenance
 ~~~~~~~~~~~~~~~~~~~~~~~~