refactor: simplify the example for 061

Author: tanishiking

examples/061_TopLevelCantBeImplicitID.scala

@@ -3,7 +3,6 @@
 @main def TopLevelCantBeImplicitID = ()
 
 import scala.language.implicitConversions
-case class C(str: String)
-implicit def toC(x: String): C = C(x)
-implicit val defaultC: C = C("default")
+implicit def intToBoolean(x: Int): Boolean = x != 0
+implicit val foo: String = "foo"
 // END