docs: add link to other repos

Author: sgratzl

README.md

@@ -4,10 +4,19 @@
 
 Chart.js module for adding a new categorical scale which mimics a hierarchical tree.
 
-**Works only with Chart.js >= 3.0.0**
-
 ![hierarchy](https://user-images.githubusercontent.com/4129778/41763778-6722e04a-75ff-11e8-84ad-1b417fd25c65.gif)
 
+## Related Plugins
+
+Check out also my other chart.js plugins:
+ * [chartjs-chart-boxplot](https://github.com/sgratzl/chartjs-chart-boxplot) for rendering boxplots and violin plots
+ * [chartjs-chart-error-bars](https://github.com/sgratzl/chartjs-chart-error-bars) for rendering errors bars to bars and line charts
+ * [chartjs-chart-geo](https://github.com/sgratzl/chartjs-chart-geo) for rendering map, bubble maps, and choropleth charts
+ * [chartjs-chart-graph](https://github.com/sgratzl/chartjs-chart-graph) for rendering graphs, trees, and networks
+ * [chartjs-chart-pcp](https://github.com/sgratzl/chartjs-chart-pcp) for rendering parallel coordinate plots
+ * [chartjs-chart-venn](https://github.com/sgratzl/chartjs-chart-venn) for rendering venn and euler diagrams
+ * [chartjs-chart-wordcloud](https://github.com/sgratzl/chartjs-chart-wordcloud) for rendering word clouds
+
 ## Install
 
 ```bash