Improve test/README.md with instructions for ignoring not-yet-implemented tests

Author: lukewagner

test/README.md

@@ -4,14 +4,18 @@ This directory contains Component Model reference tests, grouped by functionalit
 
 ## Running in Wasmtime
 
-(Until the `component-model-async` and `component-model-async-builtins` features
-are enabled by default, they must be explicitly enabled as shown below.)
-
 A single `.wast` test can be run with full backtrace on trap via:
 ```
 WASMTIME_BACKTRACE_DETAILS=1 wasmtime wast -W component-model-more-async-builtins=y -W component-model-threading=y -W component-model-async-stackful=y -W component-model-implements=y the-test.wast
 ```
+
 All the tests can be run from this directory via:
 ```
 find . -name "*.wast" | xargs wasmtime wast -W component-model-more-async-builtins=y -W component-model-threading=y -W component-model-async-stackful=y -W component-model-implements=y
 ```
+
+Sometimes tests are landed ahead of the implementation and fail for a while.
+These tests are listed in 'nyi.txt' and can be filtered out via:
+```
+find . -name "*.wast" | grep -vxFf nyi.txt | xargs wasmtime wast -W component-model-more-async-builtins=y -W component-model-threading=y -W component-model-async-stackful=y -W component-model-implements=y
+```

test/nyi.txt

@@ -0,0 +1,5 @@
+# See README.md
+./wasm-tools/memory64.wast
+./wasm-tools/resources.wast
+./async/trap-if-sync-and-waitable-set.wast
+./async/trap-if-transfer-in-waitable-set.wast