Fix typo in readme (#83)

diff --git a/README.md b/README.md
index 8277cee..d08395b 100644
--- a/README.md
+++ b/README.md
@@ -132,7 +132,7 @@
 ```
 pushd $OPENWHISK_HOME
 ./gradlew install
-podd $OPENWHISK_HOME
+popd $OPENWHISK_HOME
 ```
 
 Using gradle to run all tests