Notice for users of cloudflared and db-connect from 2021.2.4

[adaptive]

Backward Incompatible Changes

• [db-connect] Removes db-connect from cloudflared . The Cloudflare Workers product will continue to support db-connect implementations with versions of cloudflared that predate this release and include support for db-connect.

https://github.com/cloudflare/cloudflared/blob/master/CHANGES.md