Update gcloud.rst
Add note about not being able to use Uniform access control on google cloud bucket
@@ -133,6 +133,9 @@ a signed (expiring) url.
GS_DEFAULT_ACL must be set to 'publicRead' to return a public url. Even if you set
the bucket to public or set the file permissions directly in GCS to public.
+.. note::
+ When using this setting, make sure you have ``fine-grained`` access control enabled on your bucket,
+ as opposed to ``Uniform`` access control, or else, file uploads will return with HTTP 400.
``GS_FILE_CHARSET`` (optional)
