Fix issue with visiting Chef Supermarket results

This corrects the URL that Alfred sends you to, to be the actual
Supermarket page for a cookbook, instead of the API result for a
particular cookbook.

Makes for a much friendlier experience.
Add screenshot and example illustrating Chef Supermarket search
Merge pull request #25 from jeffbyrnes/fix-chef-search

Fix the URL to visit from a Chef Supermarket search