add version note

README.Rmd

@@ -26,6 +26,29 @@ library(magrittr)
 library(data.table)
 library(ggplot2)
 library(knitr)
+
+## code to determine version inspired by [pkgdown:::dev_mode_auto()]
+version <- packageVersion("scoringutils")
+devel <- length(unclass(package_version(version))[[1]]) > 3
+```
+
+```{r warn_dev, results='asis'}
+if (devel)) {
+  cat(
+    "This documentation refers to the development version of scoringutils.",
+    "For the latest CRAN release please refer to the ",
+    "[documentation of the stable version]",
+    "(https://epiforecasts.io/scoringutils)."
+  )
+} else {
+  cat(
+    "This documentation refers to the RAN version of scoringutils.",
+    "For the version on GitHub please refer to the ",
+    "[documentation of the development version]",
+    "(https://epiforecasts.io/scoringutils/dev)."
+  )
+}
+cat("\n\n")
 ```
 
 The `scoringutils` package provides a collection of metrics and proper scoring rules and aims to make it simple to score probabilistic forecasts against the true observed values.