build: improve `make clean`

also undocument the `vcbuild.bat` command since it's broken
and seems to only be relevant to release builds

PR-URL: https://github.com/nodejs/node/pull/16372
Refs: https://github.com/nodejs/node/pull/16010
Refs: https://github.com/nodejs/node/issues/16278


Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>