README for asyncWhere

pkgs/stream_transform/README.md

diff --git a/pkgs/stream_transform/README.md b/pkgs/stream_transform/README.md
index 0c64087..bf69198 100644
--- a/pkgs/stream_transform/README.md
+++ b/pkgs/stream_transform/README.md
@@ -1,6 +1,10 @@
 Contains utility methods to create `StreamTransfomer` instances to manipulate
 Streams.
 
+# asyncWhere
+
+Like `where` but allows an asynchronous predicate.
+
 # audit
 
 Audit waits for a period of time after receiving a value and then only emits
@@ -41,4 +45,4 @@
 
 # throttle
 
-Blocks events for a duration after an event is successfully emitted.
\ No newline at end of file
+Blocks events for a duration after an event is successfully emitted.