The top-level documentation site for httk₂, published to the root of
docs.httk.org. It introduces the toolkit and links to each
module; the detailed API reference for every module lives on its own per-module
subsite (e.g. docs.httk.org/httk-core/, docs.httk.org/httk-atomistic/).
Build the documentation incrementally with make docs. For a clean, forced
rebuild, use make docs-full. The incremental build skips the per-module
source pages (sphinx.ext.viewcode, which re-highlights every module on every
build); make docs-full — the published form — includes them
(HTTK_DOCS_VIEWCODE=1).