Issue1002 - Create lake & etl readme

[idiom-bytes]

Fixes #1002

Changes proposed in this PR:

• [x] Communicated basics of lake, etl, and overall predictoor job into a readme.
• [x] Communicated how these components are different from each other, and how they work together.
• [x] Communicated checkpoint details about [GQLDF CSV + RAW] providing end-to-end requirements for how we keep this updated.
• [ ] Communicated checkpoint details about [RAW => ETL Tables] providing end-to-end requirements for how we keep this updated.
• [ ] Communicate a bit about CLI commands, and how they work.
• [ ] An end-to-end example with lake update raw
• [ ] An end-to-end example with lake update etl
• [ ] Update vs. Drop vs. other commands
• [ ] Create basic visuals for each section, to provide a mental model.

[KatunaNorbert]

Reviewed the README and have some feedback:

• [ ] Add information about where the data comes from and what kind of data we are ingesting into the lake
• [ ] 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
• [ ] 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]

I'm having to draw a bunch of diagrams... targeting to deliver this when @kdetry is further along w/ integration. Currently focusing on #1001 and advancing the ETL.

[idiom-bytes]

README has been concluded inside PR #1001, closing PR and updating ticket