docs: fix a tiny typo in the README (#20)

Author: davidsansome

packages/google-cloud-iam/README.rst

@@ -83,7 +83,7 @@ Next Steps
 ~~~~~~~~~~
 
 -  Read the `Client Library Documentation`_ for IAM API
-   API to see other available methods on the client.
+   to see other available methods on the client.
 -  Read the `IAM API Product documentation`_ to learn
    more about the product and see How-to Guides.
 -  View this `repository’s main README`_ to see the full list of Cloud