Update docs for march 2024

[pinheadmz]

Currently includes basic cleanup of the markdown files and introduction page. Also updated a few RPC command help texts, revised scripts/apidocs.py and ran it.

TODO:

• [x] Add edge_schema.json and validate edges with it (important for LN channels)
• [x] Add a new script like apidocs.py that parses the schema files and automatically documents in graph.md including an example of all the <key attr.name=... headers that are needed in each graphml file
• [ ] Add another script that parses the justfile and automatically documents those, maybe in a new kubernetes.md file
• [ ] Finally, make sure our installation instructions are still accurate

[pinheadmz]

marking as ready for now, will check installation and k8s docs in a future PR