Fix typo in filename used in 'docs/auth.md'. (#736)

diff --git a/docs/oauth.md b/docs/oauth.md
index 947c4ac..71874c9 100644
--- a/docs/oauth.md
+++ b/docs/oauth.md
@@ -33,7 +33,7 @@
 
 ### flow_from_clientsecrets()
 
-The [oauth2client.client.flow_from_clientsecrets()](http://oauth2client.readthedocs.org/en/latest/source/oauth2client.client.html#oauth2client.client.flow_from_clientsecrets) method creates a `Flow` object from a [client_secrets.json](client_secrets.md) file. This [JSON](http://www.json.org/) formatted file stores your client ID, client secret, and other OAuth 2.0 parameters.
+The [oauth2client.client.flow_from_clientsecrets()](http://oauth2client.readthedocs.org/en/latest/source/oauth2client.client.html#oauth2client.client.flow_from_clientsecrets) method creates a `Flow` object from a [client_secrets.json](client-secrets.md) file. This [JSON](http://www.json.org/) formatted file stores your client ID, client secret, and other OAuth 2.0 parameters.
 
 The following shows how you can use `flow_from_clientsecrets()` to create a `Flow` object:
 
@@ -177,4 +177,4 @@
 flags = parser.parse_args()
 ...
 credentials = tools.run_flow(flow, storage, flags)
-```
\ No newline at end of file
+```