Constant SKIPPED 

const SKIPPED: [&str; 8];

Directory names never descended into.

target and site are build output; .git is the object store. docs/design is the internal design corpus (D25), exempt for the reason the module docs give: §1.3.80 is the fact that records the repository form and has to quote it. The rest are caches a Python or Node toolchain leaves behind, which are not the repository’s documentation in any sense.