Make cpp_info transitive information more clear when using components

When reading the cpp_info page in Conan docs (https://docs.conan.io/2.0/reference/conanfile/methods/package_info.html) we can find explanation about cpp_info attributes and about components, but not about the transitive between them.

It would be great detailing what could be accessed via cpp_info, when having a component. For instance:

The package A has `cpp_info.components["foo"].bindirs = ["lib/foo"]`.

- Will this bindir be available via `cpp_info.bindirs` (the global one)?
- When consuming package A, its `cpp_info.bindirs` will be available when using `VirtualBuildEnv` or `VirtualRunEnv` when not declaring `A::foo` in my cpp_info requires?

/cc @garethsb

Start with the cpp_info and components sections on the linked package_info.html page. Verify how component bindirs flow to global cpp_info.bindirs and how VirtualBuildEnv or VirtualRunEnv handle package A without A::foo in cpp_info.requires; update the documentation to answer both cases clearly.

Written by the indexing model from the issue text.