Fix typo in async/README.md

Reviewed By: yfeldblum

Differential Revision: D5802013

fbshipit-source-id: 472b09da2be7234157a7886018004e2f4ed4f279

diff --git a/folly/io/async/README.md b/folly/io/async/README.md
index d2841a06961df3c4fc2f6f24387bc014b10388b8..48de55f3ab6055dc2dc2059e826ac8acfd09bc29 100644 (file)
--- a/folly/io/async/README.md
+++ b/folly/io/async/README.md
@@ -216,7 +216,7 @@ multiple timeouts using a single fd.
 
 #### HHWheelTimer
 
-Implementation of a [hashed hierarcical wheel
+Implementation of a [hashed hierarchical wheel
 timer](http://www.cs.columbia.edu/~nahum/w6998/papers/sosp87-timing-wheels.pdf).
 Any timeout time can be used, with O(1) insertion, deletion, and
 callback time.  The wheel itself takes up some amount of space, and