Previously the build doc was a gigantic list of modules and properties,
which can be overwhelming to new users. This change breaks it up by
packages, so that it is easier to look up and feels more coherent.
Bug: 123521276
Test: m soong_docs
Change-Id: I1a1a331f4b4deb8782d698e9076098c5a27b9566
Add a rule in soong that re-executes soong_build in order to
generate build documentation. This allows Soong to customize
the documentation.
Bug: 70516282
Test: m soong_docs
Change-Id: If143cfacd6ac20274cd7bb8d8fab0c07025a5553