Changes

* [https://support.mozilla.com/en-US/kb/How+to+make+Firefox+the+default+browserHow+to+make+Firefox+the+default+browser]* [https://support.mozilla.com/en-US/kb/Using+the+spell+checkerUsing+the+spell+checker]* [https://support.mozilla.com/en-US/kb/Options+window+-+Advanced+panelOptions+window+-+Advanced+panel]