Missing (important) class attributes

Some important class attributes are not listed in the documentation which could be relevant to users.

The Future class (https://docs.ocean.dwavesys.com/projects/cloud-client/en/latest/reference/computation.html#class) for example does not list in its documentation the attributes "error" or "remote_status", though the problem status is referred to in the description for 'Computation':

> You can interact through the Future object with pending (running) or completed computation—sampling on a QPU or software solver—executed remotely, monitoring **problem status**, waiting for and retrieving results, cancelling enqueued jobs, etc.