Use mdoc also on conversion snippet

Author: mariogalic

_overviews/collections-2.13/conversion-between-option-and-the-collections.md

@@ -35,16 +35,14 @@ implicit def option2Iterable[A](xo: Option[A]): Iterable[A]
 
 so although `Option[A]` is not a full collection it can be _viewed_ as one. For example,
 
-```
-scala> Some(42).drop(1)
-val res0: Iterable[Int] = List()
+```scala mdoc
+Some(42).drop(1)
 ```
 
 expands to
 
-```
-scala> Option.option2Iterable(Some(42)).drop(1)
-val res1: Iterable[Int] = List()
+```scala mdoc
+Option.option2Iterable(Some(42)).drop(1)
 ```
 
 because `drop` is not defined on `Option`. A downside of the above implicit conversion is that instead of getting back an `Option[A]` we are left with an `Iterable[A]`. For this reason, `Option`’s documentation carries the following note: