[Chips] Fix documentation for flow layout class
[Chips] Fix documentation for flow layout class

The docs mentioned `ChipCollectionViewLayout` which was the incorrect class name. The correct name is `MDCChipCollectionViewFlowLayout`.

Closes #3206
randallli/material-components-ios,randallli/material-components-ios,sigito/material-components-ios,randallli/material-components-ios,randallli/material-components-ios,material-components/material-components-ios,randallli/material-components-ios,material-components/material-components-ios,material-components/material-components-ios,material-components/material-components-ios,sigito/material-components-ios,sigito/material-components-ios,material-components/material-components-ios,sigito/material-components-ios,randallli/material-components-ios,sigito/material-components-ios