use prompt instead of approval_prompt in docs

Author: aliva

docs/examples/google.rst

@@ -29,7 +29,7 @@ a callback URL then you can try out the command line interactive example below.
     >>> authorization_url, state = google.authorization_url(authorization_base_url,
     ...     # offline for refresh token
     ...     # force to always make user click authorize
-    ...     access_type="offline", approval_prompt="force")
+    ...     access_type="offline", prompt="select_account")
     >>> print 'Please go here and authorize,', authorization_url
 
     >>> # Get the authorization verifier code from the callback url

docs/examples/real_world_example_with_refresh.rst

@@ -58,7 +58,7 @@ trivial to transfer to any other web framework and provider.
         authorization_url, state = google.authorization_url(authorization_base_url,
             # offline for refresh token
             # force to always make user click authorize
-            access_type="offline", approval_prompt="force")
+            access_type="offline", prompt="select_account")
 
         # State is used to prevent CSRF, keep this for later.
         session['oauth_state'] = state

docs/oauth2_workflow.rst

@@ -68,9 +68,9 @@ the provider is Google and the protected resource is the user's profile.
                               scope=scope)
     >>> authorization_url, state = oauth.authorization_url(
             'https://accounts.google.com/o/oauth2/auth',
-            # access_type and approval_prompt are Google specific extra
+            # access_type and prompt are Google specific extra
             # parameters.
-            access_type="offline", approval_prompt="force")
+            access_type="offline", prompt="select_account")
 
     >>> print 'Please go to %s and authorize access.' % authorization_url
     >>> authorization_response = raw_input('Enter the full callback URL')
@@ -163,17 +163,17 @@ Backend Application Flow
 The steps below outline how to use the Resource Owner Client Credentials Grant Type flow to obtain an access token.
 
 0. Obtain credentials from your OAuth provider. At minimum you will
-   need a ``client_id`` and ``client_secret``. 
+   need a ``client_id`` and ``client_secret``.
 
     .. code-block:: pycon
-    
+
         >>> client_id = 'your_client_id'
         >>> client_secret = 'your_client_secret'
 
 1. Fetch an access token from the provider.
 
     .. code-block:: pycon
-    
+
         >>> from oauthlib.oauth2 import BackendApplicationClient
         >>> client = BackendApplicationClient(client_id=client_id)
         >>> oauth = OAuth2Session(client=client)
@@ -183,14 +183,14 @@ The steps below outline how to use the Resource Owner Client Credentials Grant T
    If your provider requires that you pass auth credentials in a Basic Auth header, you can do this instead:
 
     .. code-block:: pycon
-    
+
         >>> from oauthlib.oauth2 import BackendApplicationClient
         >>> from requests.auth import HTTPBasicAuth
         >>> auth = HTTPBasicAuth(client_id, client_secret)
         >>> client = BackendApplicationClient(client_id=client_id)
         >>> oauth = OAuth2Session(client=client)
         >>> token = oauth.fetch_token(token_url='https://provider.com/oauth2/token', auth=auth)
-                    
+
 Refreshing tokens
 -----------------