Catalog Redesign: Addition of URL for API listings

I suggest the addition of some sort of url parameter that could cover a wide range of supporting elements for an API. These could answer a number of the questions outlined on - https://github.com/GSA/slash-developer-pages/blob/master/API_Checklist.md

Taking the example catalog entries, adding a URL of supporting elements for each:

Farmers Market Directory API:
homepage: http://search.ams.usda.gov/farmersmarkets/v1/svcdesc.html
agency: Agricultural Marketing Service
department: Agriculture
url:
- type : search
url : http://search.ams.usda.gov/farmersmarkets/Accessible.aspx
- type : terms of service
url : http://search.ams.usda.gov/farmersmarkets/v1/APITOS.html

Economic Research Service Content API:
homepage: http://ers.usda.gov/developer/website-content-api.aspx
agency: Economic Research Service
department: Agriculture
url:
- type : registration
url : https://api.data.gov/signup
- type : terms of service
url : http://ers.usda.gov/developer/api-terms-of-service.aspx
- type : widgets
url : http://ers.usda.gov/developer/widgets.aspx#.Uz76H61dUpo