add callout

Author: stephmarie17

Diff for: source/fundamentals/connections/connection-guide.txt

@@ -181,3 +181,7 @@ following behavior:
 - They require you to specify a :manual:`secondary read preference
   </core/read-preference/#mongodb-readmode-secondary>` when the
   specified host isn't the **primary** node.
+
+.. note:: Replica Set in Docker
+
+   .. sharedinclude:: dbx/docker-replica-set.rst