Segmented control interface guidelines (#276)

* adds first draft of segmented control guidelines

* adds custom video player

* formats segmented control guidelines

* adds segmented control info to saving guidelines

* Update content/components/segmented-control.mdx

Co-authored-by: simurai <[email protected]>

* Update content/components/segmented-control.mdx

Co-authored-by: simurai <[email protected]>

* addresses PR feedback and fixes video player bug

* Update content/components/segmented-control.mdx

Co-authored-by: simurai <[email protected]>

* corrects keyboard navigation video example

Co-authored-by: simurai <[email protected]>

Author: mperrotti