fix README Example Usage Command (#4)

seike460 · web-flow · commit 17ed2c1762d1 · 2022-10-18T11:49:02.000+09:00
diff --git a/README.md b/README.md
@@ -40,7 +40,7 @@ Options:
 ### Command
 
 ```
-$ openapi-rq -p ./petstore.yaml
+$ openapi-rq -i ./petstore.yaml
 ```
 
 ### Output directory structure
