Add 'Improve this translation' link to the pages

Lots of people complains about translations being incorrect, but they don't have time for embarking on the whole process of becoming a Tor translator, or simply dont know how to find the particular string they want to change.

So, we can add a link on the bottom navigation bar to access the translations for that particular page.

This will lead to better reviewed strings, and hopefully make them better. We will also need to respond quickly to the suggestions.

@gus says this will be used by a lot of people that complains about translations.