fix up the reference index

Author: dajmcdon

DESCRIPTION

@@ -19,6 +19,7 @@ Description: A forecasting "framework" for creating epidemiological forecasts
 License: MIT + file LICENSE
 URL: https://github.com/cmu-delphi/epipredict/,
     https://cmu-delphi.github.io/epipredict
+BugReports: https://github.com/cmu-delphi/epipredict/issues/
 Depends: 
     R (>= 3.5.0)
 Imports: 

_pkgdown.yml

@@ -22,7 +22,8 @@ reference:
   - title: Forecast postprocessing
     desc: Create a series of postprocessing operations
     contents:
-    - contains("frosting")
+    - frosting
+    - ends_with("_frosting")
     - get_test_data
   - title: Frosting layers
     contents: