Merge pull request #829 from mlr-org/pkgdown_vignettes

_pkgdown.yml with vignettes

pkgdown/_pkgdown.yml

@@ -16,14 +16,19 @@ toc:
 
 navbar:
   structure:
-    left: [reference, news, book]
+    left: [reference, articles, news, book]
     right: [search, github, mattermost, stackoverflow, rss, lightswitch]
   components:
     home: ~
     reference:
       icon: fa fa-file-alt
       text: Reference
       href: reference/index.html
+    articles:
+      text: Articles
+      menu:
+      - text: Adding new PipeOps
+        href: articles/extending.html
     mattermost:
       icon: fa fa-comments
       href: https://lmmisld-lmu-stats-slds.srv.mwn.de/mlr_invite/