Improve calibration user guide page

[natestemen]

We have "Calibration" as part of the core concepts page in our our documentation, but the page could be filled in further to add more details and motivation.

[nickdgardner]

Hey @nathanshammah! Is there anything I can do for this? Just let me know, happy to contribute however would be helpful (or not at all if you've got it covered)

[Misty-W]

I propose to update the Docs with more information about the functions and classes that have been added. One way to include them is with autosummary, as done here for ZNE's Factories in the User Guide. Example of the autosummary code:

.. autosummary:: :nosignatures:

~mitiq.zne.inference.LinearFactory ~mitiq.zne.inference.RichardsonFactory ~mitiq.zne.inference.PolyFactory ~mitiq.zne.inference.ExpFactory ~mitiq.zne.inference.PolyExpFactory ~mitiq.zne.inference.AdaExpFactory It could be nice to also add more details about the Settings options and the log=True option.

I also propose to include a link to the tutorial, once it gets added.