This hides:
- "use_created_date"
- "use_shared_date"
- "size_as_quota"
from the configurator (rclone config) as they interfere with normal
operations and shouldn't be set in a backend config.
They can still be put in the config file by hand and will still work
as variables, etc.
This adds some more docs to "size_as_quota" also.
Fixes#3912
Nick Craig-Wood
97ed8db75d