DOC: Add privacy policy for pandas GBQ (#264)

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Author: tswast

docs/source/howto/authentication.rst

@@ -76,6 +76,7 @@ See the `Getting started with authentication on Google Cloud Platform
 <https://cloud.google.com/docs/authentication/getting-started>`_ guide for
 more information on service accounts.
 
+.. _authentication-user:
 
 Authenticating with a User Account
 ----------------------------------

docs/source/index.rst

@@ -40,6 +40,7 @@ Contents:
    api.rst
    contributing.rst
    changelog.rst
+   privacy.rst
 
 
 Indices and tables

docs/source/privacy.rst

@@ -0,0 +1,45 @@
+Privacy
+=======
+
+This package is a `PyData project <https://pydata.org/>`_ and is subject to
+the `NumFocus privacy policy <https://numfocus.org/privacy-policy>`_. Your
+use of Google APIs with this module is subject to each API's respective
+`terms of service <https://developers.google.com/terms/>`_.
+
+Google account and user data
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Accessing user data
+~~~~~~~~~~~~~~~~~~~
+
+The :mod:`pandas_gbq` module accesses your Google user account, with
+the list of `scopes
+<https://developers.google.com/identity/protocols/googlescopes>`_ that you
+specify. Depending on your specified list of scopes, the credentials returned
+by this library may provide access to other user data, such as your email
+address, Google Cloud Platform resources, Google Drive files, or Google
+Sheets.
+
+Storing user data
+~~~~~~~~~~~~~~~~~
+
+By default, your credentials are stored to a local file, such as
+``~/.config/pandas_gbq/bigquery_credentials.dat``. See the
+:ref:`authentication-user` guide for details. All user data is stored on
+your local machine. **Use caution when using this library on a shared
+machine**.
+
+Sharing user data
+~~~~~~~~~~~~~~~~~
+
+The pandas-gbq library only communicates with Google APIs. No user
+data is shared with PyData, NumFocus, or any other servers.
+
+Policies for application authors
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Do not use the default client ID when using the pandas-gbq library
+from an application, library, or tool. Per the `Google User Data Policy
+<https://developers.google.com/terms/api-services-user-data-policy>`_, your
+application must accurately represent itself when authenticating to Google
+API servcies.