Fix release guide with correct prefix dir (#11)

diff --git a/dev/README_RELEASE_CLIENT.md b/dev/README_RELEASE_CLIENT.md
index 90d260e..c00d93c 100644
--- a/dev/README_RELEASE_CLIENT.md
+++ b/dev/README_RELEASE_CLIENT.md
@@ -58,7 +58,7 @@
 - Tarball the repo
 
     ```shell script
-    git archive --format=tar.gz ${VERSION} -o airflow-client-${VERSION}-source.tar.gz
+    git archive --format=tar.gz ${VERSION} --prefix=airflow-client-${VERSION}/ -o airflow-client-${VERSION}-source.tar.gz
     ```
 
 - Generate sdist