* Add utility class for the user-select property

* Docs: Add new page for behavior utility classes - includes user select utility

* Update and rename behaviors.md to interactions.md

* Update sidebar.yml

Co-authored-by: Mark Otto <otto@github.com>
Co-authored-by: XhmikosR <xhmikosr@gmail.com>
Co-authored-by: Martijn Cuppens <martijn.cuppens@gmail.com>