docs: add repo warning

Signed-off-by: Sander Pick <sanderpick@gmail.com>

Author: sanderpick

README.md

@@ -10,6 +10,8 @@
 
 Join us on our [public Slack channel](https://slack.textile.io/) for news, discussions, and status updates. [Check out our blog](https://medium.com/textileio) for the latest posts and announcements.
 
+### WARNING: This repo is pointing to a [feature branch](https://github.com/textileio/go-threads/pull/498) of `go-threads` that handles identities as Decentralized Identifiers (DIDs) and should be considered alpha. The [textile repo](https://github.com/textileio/textile) contains the non-DID-based bucket implementation currently compatible with [Textile's public hub](https://cloud.hub.textile.io/#/access). DID-based buckets will be integrated into the hub mid 2021. In the meantime, you can still use this repo for standalone bucket peers.
+
 ## Table of Contents
 
 - [Security](#security)