refactor: Separate personas in our documentation (users vs connector developers)

[raulb]

It was brought up by @nickchomey that our documentation could be confusing at first. We don't clearly separate what's useful for a conduit user or a conduit developer.

I do agree that our docs have a mix of content - some of the things we explain are technical and detailed information that we believe are useful for Connector developers, while some other information is useful for Connector users. We should make a clear distinction in our docs so any information is user-friendly.