docs(README): Reorder content and cleanup

[janpio]

• Installation is currently unclear
• generator block works like this, but questionable if final form
• Some tiny text changes for readability
• seed first, as this is where our focus is right now

closes #11

[maticzav]

@janpio the new version doesn't have silent option anymore as we relly on Prisma to get the ids.

[janpio]

I did not touch the content at all there, just changed the order. An update to what it actually does and how it works should probably done in a separate PR - I have no real insight there.