chore(Coder plugin): Create guide for working with the Coder SDK

[Parkreiner]

Closes #112

Changes made

• Added guide

Things left to do

• [ ] Add images/video to designated areas of the draft
• [ ] Add link to the guide from the main README

Notes

• Might be helpful to view the README in the actual repo view
• I updated a couple of the other pending PRs as I was writing this out
  • There's a couple of things I'm realizing could be improved with the final design, but I'm going to make a note of them, and come back once we have more customer interest

[Parkreiner]

@Kira-Pilot Updated the READMEs: there's two main files now:

• The main guide, which is structured as a quick-start
• An advanced guide, which will be a catch-all for anything that requires more customization

There are a lot more files changed compared to before, but they're all basically file/property renames/reorganization to make things more clear

Can you let me know if the new READMEs feel a bit more scrutible?

[Parkreiner]

@Kira-Pilot Third time's the charm?