Show notification of new docs: R

assets/javascripts/news.json

@@ -1,4 +1,8 @@
 [
+  [
+    "2021-06-09",
+    "New documentation: <a href=\"/r/\">R</a>"
+  ],
   [
     "2021-05-31",
     "New documentation: <a href=\"/web_extensions/\">Web Extensions</a>"