Docs: add documentation

[vigimite]

There is a lot of documentation to be added. The docs for this project rely on mkdocs hosted on github pages and can be found in the docs directory.

The following documentation needs to be added:

• Usage -> examples for usage especially around custom datafusion contexts and including UDFs to the context
• Architecture -> needs to be cleaned up and expanded upon
• CLI -> provide usage examples
• YAML serde -> explicit examples containing all of the different variants
• JSON serde -> explicit examples containing all of the different variants

[vigimite]

added usage example and a generated schema reference: https://github.com/vigimite/aqueducts/commit/4f8d509e522277c180cc8899f74f95ad08cefaa0