PLT-1459: Updated README of marconi-chain-index and marconi-sidechain

[koslambrou]

• Rename the old marconi-chain-index README.md to README_MARCONI_DRAFT as it represents the README for the Marconi project as a whole. Will probably be used elsewhere.

• Update the marconi-sidechain README with latest changes and added some instructions on how to build it.

• Create a README for marconi-chain-index with a similar format to marconi-sidechain as they share many similar things. This will be worked on more in the future.

Note: The diff in the marconi-chain-index/README.md can be glanced over very quickly, as it's basically the same as the marconi-sidechain/README.md (minus the JSON-RPC server)

Pre-submit checklist:

• Branch
  • [ ] Tests are provided (if possible)
  • [ ] Commit sequence broadly makes sense
  • [ ] Key commits have useful messages
  • [ ] Formatting, PNG optimization, etc. are updated
  • [ ] Important changes are reflected in changelog.d of the affected packages
• PR
  • [ ] Self-reviewed the diff
  • [ ] Useful pull request description
  • [ ] Reference the ADR in the PR and reference the PR in the ADR (if revelant)
  • [ ] Reviewer requested

[eyeinsky]

I found the readme that is now renamed to draft useful when I first joined as it gave an overview of what marconi did. While the new parts on how to build and run is also useful, then maybe they could be merged instead -- as the new readme is brief on what marconi does, what it's architecture is, etc.

[koslambrou]

I found the readme that is now renamed to draft useful when I first joined as it gave an overview of what marconi did. While the new parts on how to build and run is also useful, then maybe they could be merged instead -- as the new readme is brief on what marconi does, what it's architecture is, etc.

@eyeinsky I agree that it's very valuable. However, it is not the README for marconi-chain-index, but README for the Marconi project as a whole. That draft README would essentially be the README for the marconi project once we split it in a separate repo.