Add some documentation to the resolver
Add some documentation to the resolver

This is currently my best-effort attempt to document various portions of the
resolver with the logic that's been added recently. It at least helped me
understand a bit what was going on so I hope it can help others as well!

rustyhorde/cargo,tsurai/cargo,tsurai/cargo,nipunn1313/cargo,tshepang/cargo,tsurai/cargo,nipunn1313/cargo,tsurai/cargo,vojtechkral/cargo,rust-lang/cargo,tshepang/cargo,rust-lang/cargo,eminence/cargo,eminence/cargo,vojtechkral/cargo,eminence/cargo,eminence/cargo,vojtechkral/cargo,nipunn1313/cargo,rustyhorde/cargo,tshepang/cargo,rustyhorde/cargo,rust-lang/cargo,tsurai/cargo,rust-lang/cargo,vojtechkral/cargo,rustyhorde/cargo,nipunn1313/cargo,tshepang/cargo