expose `#help options` to meta-Lean

At https://leanprover.zulipchat.com/#narrow/stream/113488-general/topic/Dots.20in.20outputs.20.2B.20documentation it was pointed out that we have no manual page listing all the configuration options.

These options are at least slightly dynamic, in that users can create new trace options, so such a page would need to be generated from compiled mathlib the same way as the rest of the docs.

Is it possible to expose the output of #help options? Unfortunately the descriptions for all of the trace options are the same; we'll have to do something there too. As a first pass we could just collect them all together under one description.

Prerequisites

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  • Reduced the issue to a self-contained, reproducible test case.

Description

[Description of the issue]

Steps to Reproduce

1. [First Step]
2. [Second Step]
3. [and so on...]

Expected behavior: [What you expect to happen]

Actual behavior: [What actually happens]

Reproduces how often: [What percentage of the time does it reproduce?]

Versions

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please include the OS and what version of the OS you're running.

Additional Information

Any additional information, configuration or data that might be necessary to reproduce the issue.

Start by locating the implementation of #help options and the documentation generation path used with compiled mathlib. Determine how the command's output can be exposed to the generated docs, including how trace options are grouped when their descriptions are identical. Done means the generated documentation contains the available configuration options and reflects dynamically registered options.