DOCSP-11760: clarify single instance (#126)

* DOCSP-11760: remove single instance mention

Author: Chris Cho

source/fundamentals/monitoring.txt

@@ -65,25 +65,17 @@ You can subscribe to any of the following SDAM events:
      - Created when the topology changes, such as an election of a new
        primary or a **mongos** proxy disconnecting.
 
-       *Not applicable to a single instance.*
-
    * - ``serverHeartbeatStarted``
      - Created prior to issuing an ``isMaster`` command to a MongoDB instance.
 
-       *Not applicable to a single instance.*
-
    * - ``serverHeartbeatSucceeded``
      - Created when the ``isMaster`` command returns successfully from a
        MongoDB instance.
 
-       *Not applicable to a single instance.*
-
    * - ``serverHeartbeatFailed``
      - Created when an ``isMaster`` command issued to a specific MongoDB
        instance fails to return a successful response
 
-       *Not applicable to a single instance.*
-
 Example Event Documents
 -----------------------
 
@@ -319,7 +311,7 @@ one of the following possible values:
      - Description
 
    * - ``Single``
-     - Single standalone instance
+     - Standalone instance
 
    * - ``ReplicaSetWithPrimary``
      - Replica set with a primary