Fix version in readme (#365)

Closes #364
diff --git a/parquet/README.md b/parquet/README.md
index d032fed..326c966 100644
--- a/parquet/README.md
+++ b/parquet/README.md
@@ -27,7 +27,7 @@
 
 ```toml
 [dependencies]
-parquet = "5.0.0-SNAPSHOT"
+parquet = "4.1.0"
 ```
 
 and this to your crate root: