Restructure docs to add dedicated documentation per component

[akashsinghal]

Right now, our Custom Resources doc folder is the only place for specific details on each of the Ratify components. Ideally, we should have a more general folder per component which can explain the purpose of each (verifier, store, etc) and then provide some user examples and CLI configs. This would be separate from the existing Custom Resources folder of docs.

Along the same lines, the existing stores.md and verifiers.md document is outdated and outlines a generic functional requirement when Ratify was originally proposed in 2021. This is no longer helpful and is largely inaccurate.