chore: update readme with prerelease warning

Author: achingbrain

README.md

@@ -13,6 +13,16 @@
 
 > Install your favourite modules from the Distributed Web using IPFS. Have a cache always ready and share them in all your local networks.
 
+## PRERELEASE WARNING:
+
+This module depends on features in the upcoming [v0.34.0](https://github.com/ipfs/js-ipfs/issues/1721) release of [js-ipfs](https://github.com/ipfs/js-ipfs) (due by the end of December 2018).
+
+If you use this module, please aslo upgrade your IPFS install with
+
+```console
+npm install -g [email protected]
+```
+
 ## Resources
 
 - [The original demo video](https://vimeo.com/147968322)