chore: GenAI Client - Update generated docs for Agent Engine and Prompts modules

PiperOrigin-RevId: 814680916

Author: sararob

gemini_docs/vertexai/vertexai.rst

@@ -27,7 +27,17 @@ Vertex AI SDK
     :undoc-members:
     :show-inheritance:
 
-.. automodule:: vertexai._genai.prompt_optimizer
+.. automodule:: vertexai._genai.agent_engines.memories
+    :members:
+    :undoc-members:
+    :show-inheritance:
+
+.. automodule:: vertexai._genai.agent_engines.sessions
+    :members:
+    :undoc-members:
+    :show-inheritance:
+
+.. automodule:: vertexai._genai.agent_engines.sessions.events
     :members:
     :undoc-members:
     :show-inheritance: