Update doc comments

Author: vanruesc

src/utils/ImmutableTimer.ts

@@ -8,12 +8,16 @@ export interface ImmutableTimer {
 
 	/**
 	 * Returns the current delta time in seconds.
+	 +
+	 + @return The current delta time.
 	 */
 
 	getDelta(): number;
 
 	/**
 	 * Returns the elapsed time in seconds.
+	 +
+	 + @return The elapsed time.
 	 */
 
 	getElapsed(): number;