Update README.md with "maintained by Plotly" badge

Author: gvwilson

README.md

@@ -1,3 +1,9 @@
 # DECTL Release Page
 
+<div align="center">
+  <a href="https://dash.plotly.com/project-maintenance">
+    <img src="https://dash.plotly.com/assets/images/maintained-by-plotly.png" width="600px" alt="Maintained by Plotly">
+  </a>
+</div>
+
 This repository contains the releases for the DECTL - Dash Enterprise Compiler.