chore: remove duplicate word in README (#235)

Author: manuel-lang

packages/google-cloud-vision/README.rst

@@ -111,7 +111,7 @@ Example Usage
 Next Steps
 ~~~~~~~~~~
 
--  Read the `Client Library Documentation`_ for Google Cloud Vision API
+-  Read the `Client Library Documentation`_ for Google Cloud Vision
    API to see other available methods on the client.
 -  Read the `Product documentation`_ to learn
    more about the product and see How-to Guides.