DOCSP-13384: update heartbeat config descriptions (#78)

* DOCSP-13384: update heartbeat config descriptions

Author: Chris Cho

source/kafka-sink-properties.txt

@@ -98,7 +98,7 @@ data to sink to MongoDB. For an example configuration file, see
        |
        | **Default**: ``false``
        | **Accepted Values**: ``true`` or ``false``
-   
+
    * - document.id.strategy.uuid.format
      - string
      - | Whether the connector should output the UUID in the ``_id`` field as a string or in the `BsonBinary <https://mongodb.github.io/mongo-java-driver/4.1/apidocs/bson/org/bson/BsonBinary.html>`__ format.
@@ -238,7 +238,7 @@ data to sink to MongoDB. For an example configuration file, see
      - | The maximum number of tasks that should be created for this connector. The connector may create fewer tasks if it cannot handle the specified level of parallelism.
 
        .. important:: Messages May Be Processed Out of Order For Values Greater Than 1
- 
+
           If you specify a value greater than ``1``, the connector
           enables parallel processing of the tasks. If your topic has
           multiple partition logs (allows consumers to read from the
@@ -250,16 +250,21 @@ data to sink to MongoDB. For an example configuration file, see
    * - heartbeat.interval.ms
      - int
      - | The length of time in milliseconds between sending heartbeat
-         messages to record the post batch resume token when no source
-         records have been published. Improves the resumability of the
+         messages. Heartbeat messages contain the post batch resume token
+         and are sent when no source records have been published in the
+         specified interval. This improves the resumability of the
          connector for low volume namespaces. Use ``0`` to disable.
        |
        | **Default**: ``0``
        | **Accepted Values**: An integer
 
    * - heartbeat.topic.name
      - string
-     - | The name of the topic to publish heartbeat messages to.
+     - | The name of the topic to publish heartbeat messages to. To enable
+         the heartbeat feature, you must provide a positive value in the
+         ``heartbeat.interval.ms`` setting. The user must consume
+         messages on this topic to track the latest offset (post batch
+         resume token).
        |
        | **Default**: ``__mongodb_heartbeats``
        | **Accepted Values**: A valid Kafka topic name

source/kafka-source.txt

@@ -340,7 +340,7 @@ an example source connector configuration file, see
        escapes the following "." character in the regular expression.
        For more information on how to build regular expressions, see the
        `Java SE documentation on Patterns <https://docs.oracle.com/javase/8/docs/api/java/util/regex/Pattern.html>`__.
-       
+
        | **Default**: ""
        | **Accepted Values**: A valid regular expression
 
@@ -421,18 +421,23 @@ an example source connector configuration file, see
 
    * - heartbeat.interval.ms
      - int
-     - The length of time in milliseconds between sending heartbeat messages to
-       record a post batch resume token when no source records have been published.
-       This can improve the resumability of the connector for low volume namespaces.
-       Use ``0`` to disable.
 
+     - | The length of time in milliseconds between sending heartbeat
+         messages. Heartbeat messages contain the post batch resume token
+         and are sent when no source records have been published in the
+         specified interval. This improves the resumability of the
+         connector for low volume namespaces. Use ``0`` to disable.
        | **Default**: ``0``
        | **Accepted Values**: An integer
 
    * - heartbeat.topic.name
      - string
-     - The name of the topic to write heartbeat messages to.
-
+     - | The name of the topic to publish heartbeat messages to. To enable
+         the heartbeat feature, you must provide a positive value in the
+         ``heartbeat.interval.ms`` setting. The connector must consume
+         messages on this topic to track the latest offset (post batch
+         resume token).
+       |
        | **Default**: ``__mongodb_heartbeats``
        | **Accepted Values**: A valid Kafka topic name