Write docstrings for sls detector ophyd classes;

Goal

It is desirable to complement the docstring of the integrated sls detector classes to understand arguments, and what effect changing will have:

class Eiger9McSAXS(DetectorBase):
....
def __init__(
        self,prefix="",
        *,
        name,
        kind=None,
        read_attrs=None,
        configuration_attrs=None,
        parent=None,
        device_manager=None,
        sim_mode=False,
        **kwargs,

This should help better understanding ophyd classes for future integrations. Mentioned in code review (!36 (comment 53957))