docs: Expose ReadChangeStreamFromSpanner in Beam Spanner documentation (#36428)

* docs: Expose ReadChangeStreamFromSpanner in Beam Spanner documentation

The `ReadChangeStreamFromSpanner` class was not being picked up by the automatic Python documentation (pydoc) generation used for the Apache Beam website.

This change explicitly adds the class to the relevant array in the Spanner connector's documentation configuration.

* Retesting

* Retesting

* Fixing PyDocs Indentation

* Fixing line too long

Author: flpablo

sdks/python/apache_beam/io/gcp/spanner.py

@@ -99,6 +99,7 @@
     'SpannerUpdate',
     'TimestampBoundMode',
     'TimeUnit',
+    'ReadChangeStreamFromSpanner',
 ]
 
 
@@ -683,8 +684,7 @@ class ReadChangeStreamFromSpanner(ExternalTransform):
   Example:
 
   with beam.Pipeline(options=pipeline_options) as p:
-    p | 
-    "ReadFromSpannerChangeStream" >> beam_spanner.ReadChangeStreamFromSpanner( 
+    p | "ReadSpannerChangeStream" >> beam_spanner.ReadChangeStreamFromSpanner( 
         project_id="spanner-project-id", 
         instance_id="spanner-instance-id", 
         database_id="spanner-database-id", 
@@ -714,32 +714,32 @@ def __init__(
       expansion_service=None,
   ):
     """
-        Reads Change Streams from Google Cloud Spanner.
-        
-        :param project_id: (Required) Specifies the Cloud Spanner project.
-        :param instance_id: (Required) Specifies the Cloud Spanner 
-          instance.
-        :param database_id: (Required) Specifies the Cloud Spanner 
-          database.
-        :param changeStreamName: (Required) The name of the Spanner 
-          change stream to read.
-        :param metadataDatabase: (Required) The database where the 
-          change stream metadata is stored.
-        :param metadataInstance: (Required) The instance where the 
-          change stream metadata database resides.
-        :param inclusiveStartAt: (Required) An inclusive start timestamp 
-          for reading the change stream.
-        :param inclusiveEndAt: (Optional) An inclusive end timestamp for 
-          reading the change stream. If not specified, the stream will be 
-          read indefinitely.
-        :param metadataTable: (Optional) The name of the metadata table used 
-          by the change stream connector. If not specified, a default table 
-          name will be used.
-        :param rpcPriority: (Optional) The RPC priority for Spanner operations. 
-          Can be 'HIGH', 'MEDIUM', or 'LOW'.
-        :param watermarkRefreshRate: (Optional) The duration at which the 
-          watermark is refreshed.
-        """
+    Reads Change Streams from Google Cloud Spanner.
+    
+    :param project_id: (Required) Specifies the Cloud Spanner project.
+    :param instance_id: (Required) Specifies the Cloud Spanner 
+      instance.
+    :param database_id: (Required) Specifies the Cloud Spanner 
+      database.
+    :param changeStreamName: (Required) The name of the Spanner 
+      change stream to read.
+    :param metadataDatabase: (Required) The database where the 
+      change stream metadata is stored.
+    :param metadataInstance: (Required) The instance where the 
+      change stream metadata database resides.
+    :param inclusiveStartAt: (Required) An inclusive start timestamp 
+      for reading the change stream.
+    :param inclusiveEndAt: (Optional) An inclusive end timestamp for 
+      reading the change stream. If not specified, the stream will be 
+      read indefinitely.
+    :param metadataTable: (Optional) The name of the metadata table used 
+      by the change stream connector. If not specified, a default table 
+      name will be used.
+    :param rpcPriority: (Optional) The RPC priority for Spanner operations. 
+      Can be 'HIGH', 'MEDIUM', or 'LOW'.
+    :param watermarkRefreshRate: (Optional) The duration at which the 
+      watermark is refreshed.
+    """
 
     super().__init__(
         self.URN,