Docs refactor (#480)

Big docs refactor! Motivation is to make it easier for people to find
resources they are looking for. To accomplish this, there are now three
main sections:

- Getting Started: steps for getting started, walking through most core
functionality
- Modules: these are different modules of functionality that langchain
provides. Each part here has a "getting started", "how to", "key
concepts" and "reference" section (except in a few select cases where it
didnt easily fit).
- Use Cases: this is to separate use cases (like summarization, question
answering, evaluation, etc) from the modules, and provide a different
entry point to the code base.

There is also a full reference section, as well as extra resources
(glossary, gallery, etc)

Co-authored-by: Shreya Rajpal <ShreyaR@users.noreply.github.com>

docs/modules/llms/integrations.rst

@@ -0,0 +1,20 @@
+Integrations
+=============
+
+The examples here are all "how-to" guides for how to integrate with various LLM providers.
+
+`Huggingface Hub <examples/huggingface_hub.html>`_: Covers how to connect to LLMs hosted on HuggingFace Hub.
+
+`Azure OpenAI <examples/azure_openai_example.html>`_: Covers how to connect to Azure-hosted OpenAI Models.
+
+`Manifest <examples/manifest.html>`_: Covers how to utilize the Manifest wrapper.
+
+
+.. toctree::
+   :maxdepth: 1
+   :glob:
+   :caption: Specific LLM Integrations
+   :name: Specific LLM Integrations
+   :hidden:
+
+   integrations/*