Public API documentation

[inge4pres]

Describe current state

We try to deploy to Github pages in this repo, as a leftover from the migration from zig-o11y.

Describe the desired state

We deploy the API documentation following the smae standards used by other OpenTelemetry repos.

Goals:

• detect how to publish documentation in the official OTel channels
• publish the same API docs generated by Zigs autodoc
• remove the current github pages workflow

[inge4pres]

While working on the modules, I found out that we can use the existing Github pages workflow to publish the docs.
In fact, the SDK docs are currently published here

https://open-telemetry.github.io/opentelemetry-zig/

We can decide if we want to keep this (and the corresponding Github workflow from point 3) or move everything out to OTel docs pages.