Fix link in the SBT projects page

Author: danicheg

docs/docs/usage/sbt-projects.md

@@ -3,4 +3,4 @@ layout: doc-page
 title: "Using Dotty with sbt"
 ---
 
-To try it in your project see the [Getting Started User Guide](./getting-started.md).
+To try it in your project see the [Getting Started User Guide](https://docs.scala-lang.org/scala3/getting-started.html).