Fix #61 (#62)

Issue was the unquoted use of %.>% in pkgdown's reference list. We should either quote it or, in this case, remove it as it does not make sense in the _Package global state_ section.

_pkgdown.yml

@@ -16,6 +16,7 @@ reference:
   - derive_seq
   - derive_study_day
   - assign_datetime
+  - generate_oak_id_vars
   - oak_id_vars
   - sbj_vars
 
@@ -54,6 +55,3 @@ reference:
 - title: Package global state
   contents:
   - clear_cache
-  - generate_oak_id_vars
-  - oak_id_vars
-  - %.>%