Update description about auth version in sample configuration

Now accept only v3.

Change-Id: Ia25846670f2d330ef8be0e9305115835736071d3
Signed-off-by: Ivan Anfimov <lazekteam@gmail.com>

Author: anfimovir

test/sample.conf

@@ -1,10 +1,8 @@
 [func_test]
 # sample config
 auth_uri = http://127.0.0.1:8080/auth/v1.0/
-## sample config for Swift with Keystone v2 API
-# For keystone v3 change auth_version to 3 and auth_prefix to /v3/
-#auth_version = 2
-#auth_uri = http://localhost:5000/v2.0/
+# sample config for Swift with Keystone API v3
+#auth_uri = http://localhost:5000/v3/
 
 # You may want to run tests against endpoints that use development certs
 # without installing the CA system-wide. Use this to trust an extra set