remove add_header_left entirely
update rd files
improve package documentation based on @wibeasley's suggestion
diff --git a/DESCRIPTION b/DESCRIPTION
index b8e17b7..4d9a369 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -33,3 +33,4 @@
     testthat
 VignetteBuilder: knitr
 RoxygenNote: 6.0.1
+Roxygen: list(markdown = TRUE)