Improve usability, or document the required click on "Save"

[aroly]

When you install the plugin and check a program's scope, you need to click "Save" before being able to add domains or URLs using the menu. This is not really intuitive...

IMO, it would be good to either:

• clearly document that in the README.
• modify the UI, maybe put the "Save" button next to the "Verify" ? And/or add a statement "you need to click save for the plugin to work properly"