Add transifex-client config (#830)

.tx/config

@@ -0,0 +1,9 @@
+[main]
+host = https://www.transifex.com
+
+[threema-web.threema-web]
+file_filter = public/i18n/<lang>.json
+minimum_perc = 90
+source_file = public/i18n/en.json
+source_lang = en
+type = KEYVALUEJSON

RELEASING.md

@@ -3,9 +3,10 @@
 Major release with backwards incompatible changes? Check for `TODO` comments
 with deprecations. Remove them if possible.
 
-Update translations:
+Update translations (https://github.com/transifex/transifex-client/):
 
-    $ # Download translation files from transifex.com
+    $ tx pull --all
+    $ git diff public/i18n/
     $ git add public/i18n/
     $ git commit -m 'Update translation strings from Transifex'