README: Link to project board under Roadmap

Author: magjac

README.md

@@ -78,6 +78,12 @@ Lists both bugs and enhancement requests.
 
 ## Roadmap ##
 
+There are numerous cool features missing. They are or will be listed as [enhancement requests](https://github.com/magjac/graphviz-visual-editor/labels/enhancement) on [GitHub](https://github.com/magjac/graphviz-visual-editor).
+
+There is also a [project board](https://github.com/magjac/graphviz-visual-editor/projects/1) showing the short-term activities.
+
+The medium-term plan is:
+
 * Implement some of the nicest-to-have features, learn from that and rework the UI.
 * Provide documentation.
 * Open up for collaboration.