Organize LAMBKIN documentation

[hidmic]

Description

Thanks to https://github.com/ekumenlabs/RnD/issues/83, lambkin has some documentation, but there's none about lambkin moving parts (split across technologies) nor there's a policy to keep things easily accessible.

We need to improve this. Likely depends on #17.

Definition of Done

• Use Sphinx to generate lambkin project documentation
• Make existing documentation available to Sphinx
• Revisit Python codebase, make sure docstrings are in place
• Figure out how to document RobotFramework extensions

[hidmic]

One important bit that I purposefully kept out: we should build and deploy such documentation to Github Pages (assuming that project pages can be generated in our current tier).

[hidmic]

This should probably wait for #44.