Documentation required for Nuget Client SDK classes

[NavinAT]

Please provide documentation for 'https://github.com/NuGet/NuGet.Client/tree/dev/src' NuGet Client SDK classes.
In Microsoft link 'https://learn.microsoft.com/en-us/nuget/what-is-nuget' couldn't find the class (definition, methods and properties) related information.

There are many classes in 'NuGet.Protocol dll' (more repository, providers & resources).

1. What are the uses of 'Repository, Providers, & Resources'?
2. How to work with local folder's and gallery's - Nupkg?
3. How to work with cache?
4. Some 'providers & resources - classes' have 'V2/V3': why do you have both?

Is there any proper documentation for this Nuget Client library.

FYI:
According to this link 'https://learn.microsoft.com/en-us/nuget/reference/nuget-client-sdk#third-party-documentation' - it covers only the basic information.