[SPARK-7883] [DOCS] [MLLIB] Fixing broken trainImplicit Scala example in MLlib Collaborative Filtering documentation.

Fixing broken trainImplicit Scala example in MLlib Collaborative Filtering documentation to match one of the possible ALS.trainImplicit function signatures.

Author: Mike Dusenberry <[email protected]>

Closes apache#6422 from dusenberrymw/Fix_MLlib_Collab_Filtering_trainImplicit_Example and squashes the following commits:

36492f4 [Mike Dusenberry] Fixing broken trainImplicit example in MLlib Collaborative Filtering documentation to match one of the possible ALS.trainImplicit function signatures.

Author: dusenberrymw

docs/mllib-collaborative-filtering.md

@@ -107,7 +107,8 @@ other signals), you can use the `trainImplicit` method to get better results.
 
 {% highlight scala %}
 val alpha = 0.01
-val model = ALS.trainImplicit(ratings, rank, numIterations, alpha)
+val lambda = 0.01
+val model = ALS.trainImplicit(ratings, rank, numIterations, lambda, alpha)
 {% endhighlight %}
 </div>