FR: Source maps for docs

Add a source map to the doc generation process so that reference docs can link directly into source files for each function/constant/etc.

Start by locating the documentation generation process in the repository and inspect how reference docs are produced for functions and constants. Determine where a source map would be emitted and how generated links should point into source files. Done means reference documentation links directly to the corresponding source locations.

Written by the indexing model from the issue text.