Adding docstrings and introducing sphinx draft

[giograno]

We released our first few releases on the Python SDK, but we lack proper documentation.
This PR introduces a documentation site built with sphinx.

Changes

• Adding docstrings. They are needed for the sphinx.ext.autodoc plugin (to generate the API reference);
• Introducing a minimal structure for the website generated by sphinx. It includes a brief installation guide, a link to our Python SDK page in our docs, and autogenerated API references.
• Adding a workflow that: i) generates the website; ii) pushes the built HTML files on a gh-pages branch. From this branch, we can easily create a static website on GH pages.

[alexrashed]

Awesome! Nice push towards industry-standard auto-generated SDK docs! 🚀

I only added a few comments, mostly general questions on the initial setup and the usage of Sphinx. Nothing blocking a merge / an initial deployment from my side though! 💯

I think it's necessary to get the docs as close to the actual code to make sure that it really stays in sync! 💯 Considering the state of the SDK and the potential to grow in docs, I think it would be absolutely reasonable (at least in the first place) to have its own docs pages published via GH pages and linked from docs.localstack.cloud. 👍🏽

Would be great to get the input from @HarshCasper on this topic: How whould the auto-generated API documentation for the SDK be linked with the docs / how should the two relate to each other from the perspective of developer relations?

[alexrashed]

question: ‏Should this maybe also just use the sphinx "catch all make target" in line 20 of the Makefile in the docs folder?