Using more UI agnostic language in licensing notice

Some skins (such as Minerva) may not have a "Save page" button, but
may use some other UI element. Changing "By clicking the
'{{int:savearticle}}' button" to "By saving changes", so that it is
UI agnostic.

Change-Id: Ic5eae6ed86bac87716454644ea053bf8796b20c6
Merge "Using more UI agnostic language in licensing notice"