Acknowledge HDRUK Gateway in this package as a data source

[RayStick]

https://devguide.ropensci.org/pkg_building.html

If your package connects to a data source or online service, or wraps other software, consider that your package README may be the first point of entry for users. It should provide enough information for users to understand the nature of the data, service, or software, and provide links to other relevant data and documentation. For instance, a README should not merely read, “Provides access to GooberDB,” but also include, “…, an online repository of Goober sightings in South America. More information about GooberDB, and documentation of database structure and metadata can be found at link”.

If your package provides access to a data source, we require that DESCRIPTION contains both (1) A brief identification and/or description of the organisation responsible for issuing data; and (2) The URL linking to public-facing page providing, describing, or enabling data access (which may often differ from URL leading directly to data source).