Codifies the systematic documentation of public items with the API docs
in mind, based on the incidents from the last session: backticks around
every type (Option<Self>, Arc<Mesh>, [f32; 3]) to avoid unresolved-link
and unclosed-HTML-tag warnings, one doc comment per public item, the
#![warn(missing_docs)] policy, verifying '0 warnings' via cargo doc
before committing, and doc-test conventions (rust vs ignore blocks).
Applies to wsg-lib development from now on.
Jérôme Bousquié
jerome