BUG: parameters should be documented in docstring / help

[bsipocz]

e.g. this is inadequate, the parameter descriptions should be exposed to the users (after all that is what they are after). I haven't checked, but this may be wider spread than just SIA.

>>> import pyvo
>>> irsa_SIA = pyvo.dal.SIA2Service('https://irsa.ipac.caltech.edu/SIA')
>>> irsa_SIA.search?
Signature:
irsa_SIA.search(
    pos=None,
    band=None,
    time=None,
    pol=None,
    field_of_view=None,
    spatial_resolution=None,
    spectral_resolving_power=None,
    exptime=None,
    timeres=None,
    publisher_did=None,
    facility=None,
    collection=None,
    instrument=None,
    data_type=None,
    calib_level=None,
    target_name=None,
    res_format=None,
    maxrec=None,
    session=None,
    **kwargs,
)
Docstring:
Performs a SIA2 search against a SIA2 service

See Also
--------
pyvo.dal.sia2.SIA2Query
File:      ~/munka/devel/pyvo/pyvo/dal/sia2.py
Type:      method