Simplify `generate_docs.py` to no longer require manually generating the input data (#11363)
Simplify `generate_docs.py` to no longer require manually generating the input data (#11363)

Before, you had to run `./pants help-all` to manually generate the data. This can be automated, so long as we use the `--concurrent` flag (aka `--no-pantsd`).

[ci skip-rust]
jsirois/pants,benjyw/pants,benjyw/pants,pantsbuild/pants,pantsbuild/pants,pantsbuild/pants,pantsbuild/pants,benjyw/pants,jsirois/pants,benjyw/pants,pantsbuild/pants,jsirois/pants,benjyw/pants,benjyw/pants,pantsbuild/pants,benjyw/pants,pantsbuild/pants