Update package.json for sortable library

Copied fields from sortable package.json and added additional fields for clarity.
This is in response to the initial recommendation on pull request #2965 to confirm library origin location.

- Sorry, I'm new to the npm package specification, and initially only added fields as specified in the cdnjs package schema.  After referencing the npm documentation, I added additional ones to clarify the library's author, license, and repository location.