Update tests/README.md with more details

Author: lukewagner

test/README.md

@@ -4,7 +4,14 @@ This directory contains Component Model reference tests, grouped by functionalit
 
 ## Running in Wasmtime
 
+All tests currently run and (except temporarily while spec changes are rolling out)
+pass using the [`dev` release of `wasip3-prototyping`](https://github.com/bytecodealliance/wasip3-prototyping/releases/tag/dev).
+
 A single `.wast` test can be run via:
 ```
 wasmtime wast -W component-model-async=y the-test.wast
 ```
+All the tests can be run from this directory via:
+```
+find . -name "*.wast" | xargs wasmtime-p3 wast -W component-model-async=y
+```