Update Scastie link to start with Dotty enabled

Author: nicolasstucki

docs/_includes/getting-started.html

@@ -2,7 +2,7 @@
     <div class="centered questions">
 
         <h1 id="getting-started">Try Dotty</h1>
-        <p>Try it in your browser with <a href="https://scastie.scala-lang.org/">Scastie</a> by changing the target to Dotty in the Build Settings.</p>
+        <p>Try it in your browser with <a href="https://scastie.scala-lang.org/?target=dotty">Scastie</a>.</p>
 
 
         <h1 id="getting-started-with-a-project">Create a Dotty Project</h1>