Language file modification

[cesagonchu]

Please remember to add language file changes here:
docs/lang_diff.txt
I'm in the middle of translating and it's disruptive to my work if I have to double-check everything with every update you send to Github.

For example, this file was modified two days ago:
htdocs/install/language/english/welcome.php

[mambax7]

Thanks for the reminder, will do!