Update 'README.md'

README.md

@@ -50,6 +50,8 @@ Currently you will need to manually run tor first before running cwtch.im/ui. Us
 
 ### Add new translation
 
+0. Install the language tools if you have not already (on linux: `sudo apt-get install qttools5-dev qttools-dev-tools`)
+
 1. Edit `ui.pro` and add a new line in the variable definition for `TRANSLATIONS` like:
 
     TRANSLATIONS = i18n/translation_en.ts \