DOCSP-22867: describe ChangeStreamDocument (#406)

* DOCSP-22867: describe changestreamdocument

* first pass fixes

* DB PR fixes 1

Author: rustagir

source/fundamentals/crud/read-operations/change-streams.txt

@@ -63,8 +63,14 @@ changes in the connected MongoDB deployment.
 Example
 ~~~~~~~
 
-The following code example shows how to open a change stream and print
-change stream events whenever the data in the collection changes:
+This example shows how to open a change stream on the
+``myColl`` collection and print change stream events as they occur.
+
+The driver stores change stream events in a variable of type
+``ChangeStreamIterable``. In the following example, we specify that the
+driver should populate the ``ChangeStreamIterable`` object with ``Document``
+types. As a result, the driver stores individual change stream events as
+``ChangeStreamDocument`` objects.
 
 .. literalinclude:: /includes/fundamentals/code-snippets/change-streams/ChangeStreams.java
    :language: java
@@ -81,7 +87,7 @@ following text:
    Received a change: ChangeStreamDocument{
       operationType='insert',
       resumeToken={"_data": "825EC..."},
-      namespace=myDb.myChangeStreamCollection,
+      namespace=myDb.myColl,
       ...
    }
 

source/includes/fundamentals/code-snippets/change-streams/ChangeStreams.java

@@ -42,11 +42,11 @@ public static void main(String [] args){
 //        ChangeStreams.allFullDocumentOptions(collection);
 //        ChangeStreams.aggregationExample(collection);
     }
-    private static void openExample(MongoCollection<Document> collection) {
+    private static void openExample(MongoDatabase database) {
         // begin openChangeStreamExample
-        // The collection variable references a MongoCollection instance
-        ChangeStreamIterable<Document> changeStream = collection.watch();
+        MongoCollection<Document> collection = database.getCollection("myColl");
 
+        ChangeStreamIterable<Document> changeStream = collection.watch();
         changeStream.forEach(event ->
                 System.out.println("Received a change: " + event));
         // end openChangeStreamExample