Adds note to troubleshooting guide

Fixes language and syntax

Author: AArdeev

doc/admin/troubleshoot.rst

@@ -254,6 +254,10 @@ This issue can be fixed in two ways:
 -   Manually: :ref:`reseed <replication-master-master-reseed-replica>` one master from another by removing write-ahead logs and snapshots.
 -   Programmatically: set up a :ref:`conflict resolution trigger <replication-problem_solving>`.
 
+..  NOTE::
+
+    To avoid brain split between two masters, one of the instances may be put in the :ref:`isolated mode <_configuration_reference_isolated_mode>`.
+
 Then, restart replication as described in :ref:`Restarting replication <replication-master-master-resolve-conflict>`.
 
 

doc/reference/configuration/configuration_reference.rst

@@ -2856,13 +2856,13 @@ The isolated mode moves the instance to the read-only state, in which:
 *   The instance is disconnected from all the replication upstreams
 *   Other replicaset members exclude the isolated instance from the replication upstreams
 
-Once the mode is enabled, After any requests that try to change persistent data will fail with the ``ER_READONLY`` error.
+Once the mode is enabled, any request trying to change persistent data will fail with the ``ER_READONLY`` error.
 
 ..  NOTE::
 
-    isolated instance can't be bootstrapped (a local snapshot is required to start).
+    Isolated instance can't be bootstrapped (a local snapshot is required to start).
 
-    **Example**
+**Example**
 
     The example below shows how to isolate an instance: