DOC fix typos in estimator_checks.py

[lorentzenchr]

check_estimator has argument Estimator, but documented is a parameter estimator.

[albertcthomas]

thanks @lorentzenchr

[albertcthomas]

actually it will not be possible to pass a class from 0.24, see L560 so I am not sure that we want to change this because I believe that we will change the Estimator parameter to estimator.

[NicolasHug]

This is slightly annoying because indeed we switched from classes to instances, and we didn't want to deprecate Estimator for estimator.

Documenting estimator instead of Estimator clarifies that we expect an instance, but indeed the documented name is inconsistent with the actual parameter name. I'm not sure which is best here.

[lorentzenchr]

What about changing to

@_deprecate_positional_args
def check_estimator(estimator=None, *, generate_only=False, strict_mode=True, Estimator=None):

and also throwing a deprecation warning if Estimator=something was set?
Just an idea how to get it right in the future.

[NicolasHug]

That would be deprecating Estimator (regardless of the use of _deprecate_positional_args), which we wanted to avoid / deemed not worth it.

We can deprecate if you think it's cleaner (another PR though). I doubt anyone actually uses check_estimator(Estimator=...) anyway, so hopefully this shouldn't be a problem for any third party library

[NicolasHug]

Thanks @lorentzenchr

[thomasjpfan]

For the time being this update is needed to keep the docstring consistent with the actual argument.

LGTM