diff --git a/docs/src/main/ruby/generate_readme.sh b/docs/src/main/ruby/generate_readme.sh
index 6d0ce9dc..64c6052c 100755
--- a/docs/src/main/ruby/generate_readme.sh
+++ b/docs/src/main/ruby/generate_readme.sh
@@ -24,7 +24,14 @@ attrs = doc.attributes
 attrs['allow-uri-read'] = true
 puts attrs
 
-out = "// Do not edit this file (e.g. go instead to src/main/asciidoc)\n\n"
+out = <<-WARNING
+////
+DO NOT EDIT THIS FILE. IT WAS GENERATED.
+Manual changes to this file will be lost when it is generated again.
+Edit the files in the src/main/asciidoc/ directory instead.
+////
+
+WARNING
 doc = Asciidoctor.load_file file, safe: :unsafe, parse: false, attributes: attrs
 out << doc.reader.read