add translation credits

Insert link to Ring's Transifex project page since the list of
translation contributors can be found there.

Change-Id: Ia418c066ec0b6a258d383100f841b73604a313d4
Tuleap: #134

Credits.rtf

@@ -25,4 +25,10 @@ Simon D\'e9saulniers\
 Nicolas J\'e4ger\
 \
 Based on SFLphone's project\
+\
+
+\i0\b Translated by
+\i\b0 \
+\pard\tx566\tx1133\tx1700\tx2267\tx2834\tx3401\tx3968\tx4535\tx5102\tx5669\tx6236\tx6803\pardirnatural\qc
+{\field{\*\fldinst{HYPERLINK "https://www.transifex.com/savoirfairelinux/ring/"}}{\fldrslt \cf0 https://www.transifex.com/savoirfairelinux/ring/}}\
 }
\ No newline at end of file