docs: add information on logging callback

Author: Douglas Reid

README.md

@@ -35,6 +35,8 @@ Initial support is offered for the following (with more to follow soon):
 - LLMs
   - An adapter is provided for Steamship's OpenAI integration (`steamship_langchain.llms.OpenAI`)
   - An adapter is provided for *caching* LLM calls, via Steamship's Key-Value store (`SteamshipCache`) 
+- Callbacks
+  - A callback that uses Python's `logging` module to record events is provided (`steamship_langchain.callbacks.LoggingCallbackHandler`). This can be used with `ship logs` to access verbose logs when deployed.
 - Document Loaders
   - An adapter for exporting Steamship Files as LangChain Documents is provided (`steamship_langchain.document_loaders.SteamshipLoader`)
 - Tools

docs/adapters/callbacks.rst

@@ -0,0 +1,35 @@
+Callbacks
+=========
+
+
+======================
+LoggingCallbackHandler
+======================
+
+When developing LangChain apps locally, it is often useful to turn on verbose logging
+to help debug behavior and performance. The ``LoggingCallbackHandler`` preserves this
+capability when deploying your app to Steamship.
+
+To use the ``LoggingCallbackHandler``, set the global callback handler and set ``verbose=True`` in your chain::
+
+    from steamship_langchain.callbacks import LoggingCallbackHandler
+
+    langchain.set_handler(LoggingCallbackHandler())
+
+    ...
+
+    chain = load_qa_with_sources_chain(llm, verbose=True)
+
+
+Then, to view the logs, retrieve them with ``ship logs``::
+
+    $ ship logs -w my-workspace | jq '.entries[].message'
+
+    "Finished chain."
+    "Response data size 11315"
+    "Finished chain."
+    "Got workspace: my-workspace/..."
+    "Entering new LLMChain chain..."
+    "Prompt after formatting:\n\u001b[32;1m\u001b[1;3mGiven the following extracted parts ...
+    "Entering new StuffDocumentsChain chain..."
+

docs/index.rst

@@ -34,6 +34,8 @@ Have a look at our `Coverage Page <./getting_started/getting_started.html>`_ for
 
 - `LLMs <./adapters/llms.html>`_
 
+- `Callbacks <./adapters/callbacks.html>`_
+
 - `Document Loaders <./adapters/document_loaders.html>`_
 
 - `Chains <./adapters/chains.html>`_
@@ -53,6 +55,7 @@ Have a look at our `Coverage Page <./getting_started/getting_started.html>`_ for
 
    ./adapters/prompts.md
    ./adapters/llms.rst
+   ./adapters/callbacks.rst
    ./adapters/document_loaders.rst
    ./adapters/chains.md
    ./adapters/agents.md
@@ -75,6 +78,7 @@ Here are some of the common use cases supported by Steamship:
    :hidden:
 
    ./use_cases/chatgpt.ipynb
+   ./use_cases/question_answering.md
 
 
 Coverage and Roadmap