[SPARK-8660][ML] Convert JavaDoc style comments...

[SPARK-8660][ML] Convert JavaDoc style comments inLogisticRegressionSuite.scala to regular multiline comments, to make copy-pasting R commands easier

Converted JavaDoc style comments in mllib/src/test/scala/org/apache/spark/ml/classification/LogisticRegressionSuite.scala to regular multiline comments, to make copy-pasting R commands easier.

Author: Rosstin <asterazul@gmail.com>

Closes #7096 from Rosstin/SPARK-8660 and squashes the following commits:

242aedd [Rosstin] SPARK-8660, changed comment style from JavaDoc style to normal multiline comment in order to make copypaste into R easier, in file classification/LogisticRegressionSuite.scala
2cd2985 [Rosstin] Merge branch 'master' of github.com:apache/spark into SPARK-8639
21ac1e5 [Rosstin] Merge branch 'master' of github.com:apache/spark into SPARK-8639
6c18058 [Rosstin] fixed minor typos in docs/README.md and docs/api.md