[Lake][DuckDB] Readme and UX should be well documented and work end-to-end

[idiom-bytes]

Background / motivation

To integrate duckDB (#685)[https://github.com/oceanprotocol/pdr-backend/issues/685] the user should be able to follow the README.md, get their lake setup, and complete all the work end-to-end without any issues.

Further, if the user should experience any issues, they should be able to resolve/heal the process effortlessly.

DoD

Write README.md for updated lake, and verify that it's working end-to-end

Tasks:

• [ ] Write new lake README.md
• [ ] Test README.md end-to-end
• [ ] Documentation is working as expected

[KatunaNorbert]

Reviewed the README and have some feedback:

• [x] Add information about where the data comes from and what kind of data we are ingesting into the lake
• [x] There is no information about the data available, tables etc. I would expect to visually see the data that I'm going to get before going trough the lake setup process
• [x] Add a simple example containing the command the users has to execute to go trough the etl end to end
• [x] The README is long and we don't have any legend on the top to make it easy to see the content and navigate trough different sections. Add a legend on the top of the page, example:

[idiom-bytes]

Readme has been concluded in PR for issue #1001 -> https://github.com/oceanprotocol/pdr-backend/pull/1100