Fix typo in README.md (#43173)

diff --git a/dev/devicelab/README.md b/dev/devicelab/README.md
index 38f11fd..1dec92c 100644
--- a/dev/devicelab/README.md
+++ b/dev/devicelab/README.md
@@ -168,7 +168,7 @@
   --local-engine=[local_engine_architecture]
 ```
 
-An example of of a local engine architecture is `android_debug_unopt_x86`.
+An example of a local engine architecture is `android_debug_unopt_x86`.
 
 # Reproducing broken builds locally