[Docs Update] Make docs updates for iteration on tokenless

[matt-codecov]

Our tokenless logic is changing and docs will need to be updated accordingly.

• https://docs.codecov.com/docs/quick-start - talks about getting a repo token
• https://docs.codecov.com/docs/adding-the-codecov-token
• https://docs.codecov.com/docs/codecov-uploader#upload-token

Among other places