make-doc: newer LDoc uses `ldoc` executable instead of `ldoc.lua`
config.ld: disable LuaDoc compatibility
doc: regenerated with LDoc 1.3.12
diagnostics: capture_source_location (with tests)
regenerated all
config.ld: enabled backtick references for nicer formatting

See here for the context:
https://github.com/stevedonovan/LDoc/issues/80