add 'vclFiddle'

- signed-off-by: trimstray <trimstray@gmail.com>

README.md

@@ -573,6 +573,7 @@ Only main chapters:
 &nbsp;&nbsp;:small_orange_diamond: <a href="https://codesandbox.io/"><b>CodeSandbox</b></a> - online code editor for web application development. Supports React, Vue, Angular, CxJS, Dojo, etc.<br>
 &nbsp;&nbsp;:small_orange_diamond: <a href="http://sandbox.onlinephpfunctions.com/"><b>PHP Sandbox</b></a> - test your PHP code with this code tester.<br>
 &nbsp;&nbsp;:small_orange_diamond: <a href="https://www.repl.it/"><b>Repl.it</b></a> - an instant IDE to learn, build, collaborate, and host all in one place.<br>
+&nbsp;&nbsp;:small_orange_diamond: <a href="http://www.vclfiddle.net/"><b>vclFiddle</b></a> - is an online tool for experimenting with the Varnish Cache VCL.<br>
 </p>
 
 ##### :black_small_square: Performance