[Documentation]: iOS Swift tutorial doesn’t build (#2414)
[Documentation]: iOS Swift tutorial doesn’t build (#2414)

* docs(pkg): correct `barButtonDidTap` selector

* Revert "docs(pkg): correct `barButtonDidTap` selector"

This reverts commit bb32acf3dabdba8af14c575812574f626ab3efc5.

* docs(pkg): add unnamed argument label to `ViewController` methods

This adds the `_` unnamed argument label to the `barButtonDidTap` and
`fabDidTap` methods in the Swift example code. This fixes compilation
errors.

[skip ci]

sigito/material-components-ios,material-components/material-components-ios,willlarche/material-components-ios,samnm/material-components-ios,sigito/material-components-ios,willlarche/material-components-ios,sigito/material-components-ios,sigito/material-components-ios,material-components/material-components-ios,material-components/material-components-ios,samnm/material-components-ios,randallli/material-components-ios,material-components/material-components-ios,samnm/material-components-ios,randallli/material-components-ios,material-components/material-components-ios,randallli/material-components-ios,randallli/material-components-ios,willlarche/material-components-ios,sigito/material-components-ios,randallli/material-components-ios,samnm/material-components-ios,samnm/material-components-ios,willlarche/material-components-ios,willlarche/material-components-ios,randallli/material-components-ios