[SPARK-8274] [DOCUMENTATION-MLLIB] Fix wrong URLs in MLlib Frequent Pattern Mining Documentation

There is a mistake in the URLs of the Scala section of FP-Growth in the MLlib Frequent Pattern Mining documentation. The URL points to https://spark.apache.org/docs/latest/api/java/org/apache/spark/mllib/fpm/FPGrowth.html which is the Java's API, the link should point to the Scala API https://spark.apache.org/docs/latest/api/scala/index.html#org.apache.spark.mllib.fpm.FPGrowth

There's another mistake in the FP-GrowthModel in the same section, the link points, again, to the Java's API https://spark.apache.org/docs/latest/api/java/org/apache/spark/mllib/fpm/FPGrowthModel.html, the link should point to the Scala API https://spark.apache.org/docs/latest/api/scala/index.html#org.apache.spark.mllib.fpm.FPGrowthModel

Author: FavioVazquez <favio.vazquezp@gmail.com>

Closes #6722 from FavioVazquez/fix-wrog-urls-mllib-fpgrowth and squashes the following commits:

e1ca54d [FavioVazquez] - Fixed wrong URLs in MLlib Frequent Pattern Mining, FP-Growth Scala section
ad882a3 [FavioVazquez] Merge remote-tracking branch 'upstream/master'
f27a20b [FavioVazquez] Merge remote-tracking branch 'upstream/master'
9af7074 [FavioVazquez] Merge remote-tracking branch 'upstream/master'
edab1ef [FavioVazquez] Merge remote-tracking branch 'upstream/master'
b2e2f8c [FavioVazquez] Merge remote-tracking branch 'upstream/master'

docs/mllib-frequent-pattern-mining.md

@@ -39,11 +39,11 @@ MLlib's FP-growth implementation takes the following (hyper-)parameters:
 <div class="codetabs">
 <div data-lang="scala" markdown="1">
 
-[`FPGrowth`](api/java/org/apache/spark/mllib/fpm/FPGrowth.html) implements the
+[`FPGrowth`](api/scala/index.html#org.apache.spark.mllib.fpm.FPGrowth) implements the
 FP-growth algorithm.
 It take a `JavaRDD` of transactions, where each transaction is an `Iterable` of items of a generic type.
 Calling `FPGrowth.run` with transactions returns an
-[`FPGrowthModel`](api/java/org/apache/spark/mllib/fpm/FPGrowthModel.html)
+[`FPGrowthModel`](api/scala/index.html#org.apache.spark.mllib.fpm.FPGrowthModel)
 that stores the frequent itemsets with their frequencies.
 
 {% highlight scala %}