conanbuild.conf is not exemplified in docs

[uilianries]

New helpers for Conan 2.0 are using the file conanbuild.conf to administrate the generator (e.g. Cmake Ninja), which is mentioned in Docs, but there is no hint about its format.

For instance https://docs.conan.io/en/latest/reference/conanfile/tools/cmake/cmake.html#configure

[SSE4]

it's not obvious where file should be created. is it conan cache, or current directory? yes, some examples would be nice to illustate how should I configure that file.