Basic documentation

[ssomnath]

Can copy over most from pyUSID. Includes API generation, information about package. Does NOT include examples

[ssomnath]

documentation can be removed if it already exists in sidpy's documentation

[jeffugo]

Hey,
would love to help out with this.

[ssomnath]

Any help is appreciated, @jeffugo. Many thanks!

[gduscher]

Basic documentation is now in notebooks.
More would be better