add link to discussion thread

Author: pmeier

README.md

@@ -1,6 +1,6 @@
 # Array protocol playground
 
-This repository provides a playground for a vendorable protocol for array objects that can be used to statically as well as at runtime check for adherence to the [Array API](https://github.com/data-apis/array-api). 
+This repository provides a playground for a vendorable protocol for array objects that can be used to statically as well as at runtime check for adherence to the [Array API](https://github.com/data-apis/array-api). You can find a discussion in [this thread](https://github.com/data-apis/array-api/issues/229).
 
 `consumer.py` implements a "vendored" version of the proposed protocol and `provider` implements a dummy array object adhering to it.