add rlang authors as contributors

Author: nmdefries

DESCRIPTION

@@ -14,7 +14,9 @@ Authors@R: c(
     person("Quang", "Nguyen", role = "ctb"),
     person("Evan", "Ray", role = "aut"),
     person("Dmitry", "Shemetov", role = "ctb"),
-    person("Ryan", "Tibshirani", , "ryantibs@cmu.edu", role = c("aut", "cre"))
+    person("Ryan", "Tibshirani", , "ryantibs@cmu.edu", role = c("aut", "cre")),
+    person("Lionel", "Henry", role = "ctb", comment = "Author of included rlang fragments"),
+    person("Hadley", "Wickham", role = "ctb", comment = "Author of included rlang fragments")
   )
 Description: This package introduces a common data structure for epidemiological
     data reported by location and time, provides another data structure to