[Tails-l10n] [en] Tiny correction in testing

Hi,

I made a tiny correction in doc/first_steps/unsafe_browser.mdwn
See here :
http://repo.or.cz/w/tails/matsa.git/commitdiff/493362e0bd32c57348a4263a9680d47d6f18980f

I guess the next steps could be
- merge this file on origin/testing
- update unsafe_browser.*.po files
then we will have to 'unfuzz' this line in the french version.
Give a sign if we have to execute this last step.

cheers


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