Replace README with link to the docs

[tothmano]

No description provided.

[Licenser]

I suggest leaving the readme intact and linking it to the docs as an addition. There are a few important things to that.

1. in the rust ecosystem, it's pretty common to discover over crates.io; crates without a readme are mostly discarded and not considered.
2. this will also affect docs.rs, so people will now have to go to two places to find docs to the crate
3. it removes documentation from the integration. The language server and API plugins integrate directly with docs.rs
4. it makes updating the documentation harder as now updates need to be made in sync.

perhaps replace the first section

With a link to our axiom.co docs but leave the quickstart and features in here?

[Licenser]

<3