Typo in API Documentation

[arimgibson]

I believe I might've run into the same problem as described in #13 , was pulling my hair out trying to figure out what I was doing wrong.

On the API documentation under Getting a Single Store, the URL incorrectly says that the endpoint is https://json.psty.io/api_v1/store/<store_name>, when store should be stores.

This is a fantastic app, much better than the other JSON storage sites I've been messing around with. Thank you!