Two documentation sites, split by what you are actually trying to do: understand the platform, or write code against it. Both are public, and both are searchable.
The platform is open source under AGPL-3.0, so where the documentation stops, the source carries on.
Start here
The platform documentation explains what the system does, how the data model works, and what it takes to run it. The SDK documentation covers the client libraries, worked examples, and the full API surface in Java, Python and Rust.
Operators, architects, decision-makers
What an operational data platform is, how the model maps onto your assets, and how to run it in production.
Full-text search is built into the site.
Developers
Client libraries for Java, Python and Rust. Install, authenticate, and write your first datapoint in about five minutes.
Full-text search is built into the site.
Also written down
Task walkthroughs, the raw endpoint reference, and the source code itself.