use roxygen markdown version
diff --git a/DESCRIPTION b/DESCRIPTION
index ece269b..d71709c 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -21,3 +21,4 @@
 Imports: bookdown, ggplot2, pagedown, kableExtra, Cairo, rmarkdown, knitr, yaml
 SystemRequirements: GNU make
 RoxygenNote: 6.1.1
+Roxygen: list(markdown = TRUE)