Reformat FrameworkAdapter example code in comment

The example code shows up all on one line in the generated docs.

https://kotlinlang.org/api/latest/kotlin.test/kotlin.test/-framework-adapter/ shows

> suite('a suite', false, function() { suite('a subsuite', false, ...

Use a fenced code block with a language identifier.

libraries/kotlin.test/js/src/main/kotlin/kotlin/test/FrameworkAdapter.kt

@@ -11,6 +11,7 @@ package kotlin.test
  * The tests structure is defined using internal functions suite and test, which delegate to corresponding functions of a [FrameworkAdapter].
  * Sample test layout:
  *
+ * ```js
  * suite('a suite', false, function() {
  *   suite('a subsuite', false, function() {
  *     test('a test', false, function() {...});
@@ -18,6 +19,7 @@ package kotlin.test
  *   });
  *   suite('an ignored/pending test', true, function() {...});
  * });
+ * ```
  *
  */
 public external interface FrameworkAdapter {