Add missing type argument documentation

Author: akarnokd

src/main/java/io/reactivex/Maybe.java

@@ -2563,6 +2563,7 @@ public final <R> Flowable<R> flatMapPublisher(Function<? super T, ? extends Publ
      * <dd>{@code flatMapSingle} does not operate by default on a particular {@link Scheduler}.</dd>
      * </dl>
      *
+     * @param <R> the result value type
      * @param mapper
      *            a function that, when applied to the item emitted by the source Maybe, returns a
      *            Single

src/main/java/io/reactivex/internal/operators/maybe/MaybeFlatMapSingle.java

@@ -28,7 +28,8 @@
 
 /**
  * Maps the success value of the source MaybeSource into a Single.
- * @param <T>
+ * @param <T> the input value type
+ * @param <R> the result value type
  */
 public final class MaybeFlatMapSingle<T, R> extends Single<R> {