Typo in mllib-evaluation-metrics.md

Recall by threshold snippet was using "precisionByThreshold"

Author: Mageswaran.D <mageswaran1989@gmail.com>

Closes #9333 from Mageswaran1989/Typo_in_mllib-evaluation-metrics.md.

docs/mllib-evaluation-metrics.md

@@ -141,7 +141,7 @@ precision.foreach { case (t, p) =>
 }
 
 // Recall by threshold
-val recall = metrics.precisionByThreshold
+val recall = metrics.recallByThreshold
 recall.foreach { case (t, r) =>
     println(s"Threshold: $t, Recall: $r")
 }
@@ -1509,4 +1509,4 @@ print("Explained variance = %s" % metrics.explainedVariance)
 {% endhighlight %}
 
 </div>
-</div>
\ No newline at end of file
+</div>