As a watchlist expiry user, I want to be able to watch a page via edit, so that I can temporarily watch a page after a recent edit.
**Resources:**
* [[ https://meta.wikimedia.org/wiki/Community_Tech/Watchlist_Expiry | Watchlist Expiry project page ]]
* [[ https://wikimedia.invisionapp.com/public/share/8QYG7BMTJ#/screens/475685049 | Interactive mockup: Watch a page temporarily (via star) ]]
* [[ https://wikimedia.invisionapp.com/public/share/J911SKRX3U#/screens/475686102 | Interactive mockup: Watch a page temporarily (via edit) ]]
**Acceptance Criteria:**
* When user checks the box to "Watch this page" in edit view, a drop-down should appear/become active next to the checkbox
* The user should be able to select watch period via drop-down
* The watch period should be saved or updated based on selection