Fixing typo in example
Removing unneeded contain in example
groupBy should be group

group should be used instead of groupBy.
Merge pull request #1879 from berrygoudswaard/patch-1

groupBy should be group
Change groupBy to group in es docs
Change groupBy to group in fr docs
Change groupBy to group in pt docs
Merge pull request #1881 from berrygoudswaard/groupby-to-group

groupBy should be group