fix typo in add-ons docs
Commit from Mozilla Verbatim by user mdinic@mozilla.com.: 457 of 5474 strings translated (2 fuzzy).
amp firefox winner promo (bug 919778)
Merge pull request #1175 from ngokevin/bestoverall

amp firefox winner promo (bug 919778)
turn on payments for the US
better wrapping for add-ons promo
even better promo wrapping
widen width of promo text wrapper