Fix translate docs build. (googleapis#3688)

Author: lukesneeringer

docs/translate/client.rst

@@ -1,7 +1,7 @@
 Translation Client
 ==================
 
-.. automodule:: google.cloud.translate.client
+.. automodule:: google.cloud.translate_v2.client
   :members:
   :undoc-members:
   :show-inheritance:

nox.py

@@ -30,13 +30,13 @@ def docs(session):
     # Install Sphinx and also all of the google-cloud-* packages.
     session.chdir(os.path.realpath(os.path.dirname(__file__)))
     session.install('Sphinx >= 1.6.2', 'sphinx_rtd_theme')
+    session.install('.')
     session.install(
         'core/', 'bigquery/', 'bigtable/', 'datastore/', 'dns/', 'language/',
         'logging/', 'error_reporting/', 'monitoring/', 'pubsub/',
         'resource_manager/', 'runtimeconfig/', 'spanner/', 'speech/',
         'storage/', 'trace/', 'translate/', 'vision/',
     )
-    session.install('-e', '.')
 
     # Build the docs!
     session.run('bash', './test_utils/scripts/update_docs.sh')