import docs, change references to versal-gadget-api repo
change all references to player-api repo so that they point to gadget-api
add a link to docs.md just in case
Use relative path
Partially reverted 3d83d23

Per https://github.com/Versal/versal-gadget-api/commit/3d83d2336c0b2be573bab02cee197c78dc26201e#commitcomment-7512674
Merge pull request #10 from Versal/feature/import-docs

import docs, change references to versal-gadget-api repo