* docs: centralize documentation into helpdoc
Problem: documentation was spread across four files (README.md,
doc/oil.txt, doc/api.md, doc/recipes.md) with duplication and gaps.
User events were undocumented, and adapter docs only lived in the
README.
Solution: expand doc/oil.txt with five new sections (introduction,
requirements, adapters, recipes, events) from existing content. Trim
README to a landing page pointing to :help oil. Delete doc/api.md
and doc/recipes.md since their content now lives in the helpdoc.
Closes: barrettruth/oil.nvim#6
* build: remove docgen pipeline
Problem: the Python docgen pipeline (scripts/generate.py,
scripts/main.py, nvim_doc_tools) was designed for upstream's doc
layout and is incompatible with the centralized helpdoc structure.
It overwrites doc/oil.txt entirely and expects sections in README.md
that no longer exist.
Solution: delete the pipeline scripts (generate.py, main.py,
requirements.txt), remove the update_docs CI job, and clean up the
Makefile and .gitignore references. Linting and typechecking remain
unchanged.
