use data discovery endpoint to auto-update available censuses

[fgregg]

https://api.census.gov/data.json

[vengroff]

I'm not sure if you have seen it, but censusdis does quite a bit with U.S. Census metadata to help users discover and explore data sets, groups, and variables and understand and use the tree-based structure of variables in some groups.

You can see examples of this in

• The Querying Available Data Sets demo notebook
• the Tutorial.ipynb notebook (scroll down to the Discovering Variables - More Metadata section for details).
• a video that goes through the whole tutorial.

Finally, there is a process that scans the metadata API and builds symbolic names for all datasets into censusdis.datasets.