Scaladoc: Fix deprecated warnings

JAVA-4748

Author: rozza

driver-scala/src/main/scala/org/mongodb/scala/MapReduceObservable.scala

@@ -33,7 +33,7 @@ import scala.concurrent.duration.Duration
  * @tparam TResult The type of the result.
  * @since 1.0
  */
-@deprecated("Superseded by aggregate")
+@deprecated("Superseded by aggregate", "4.4.0")
 case class MapReduceObservable[TResult](wrapped: MapReducePublisher[TResult]) extends Observable[TResult] {
 
   /**

driver-scala/src/main/scala/org/mongodb/scala/MongoCollection.scala

@@ -461,7 +461,7 @@ case class MongoCollection[TResult](private val wrapped: JMongoCollection[TResul
    * @return a Observable containing the result of the map-reduce operation
    *         [[https://www.mongodb.com/docs/manual/reference/command/mapReduce/ map-reduce]]
    */
-  @deprecated("Superseded by aggregate")
+  @deprecated("Superseded by aggregate", "4.4.0")
   def mapReduce[C](
       mapFunction: String,
       reduceFunction: String
@@ -480,7 +480,7 @@ case class MongoCollection[TResult](private val wrapped: JMongoCollection[TResul
    * @since 2.2
    * @note Requires MongoDB 3.6 or greater
    */
-  @deprecated("Superseded by aggregate")
+  @deprecated("Superseded by aggregate", "4.4.0")
   def mapReduce[C](clientSession: ClientSession, mapFunction: String, reduceFunction: String)(
       implicit e: C DefaultsTo TResult,
       ct: ClassTag[C]

driver-scala/src/main/scala/org/mongodb/scala/model/MapReduceAction.scala

@@ -26,7 +26,7 @@ import com.mongodb.client.model.{ MapReduceAction => JMapReduceAction }
  *
  * @since 1.0
  */
-@deprecated("Superseded by aggregate")
+@deprecated("Superseded by aggregate", "4.4.0")
 object MapReduceAction {
 
   /**