Add instruction how to install languages

docs/changelog.md

@@ -11,6 +11,7 @@ Current unreleased version
 
 * Fix external diff with Flatpak
 * Fix storing repository settings correctly, because otherwise they are not applied
+* Fix language support. Languages can now be switched by adding LANG=<language> in front of the executable
 
 ----
 

docs/index.md

@@ -33,6 +33,25 @@ Remember to search for existing issues before creating a new one.
 If you still need help, check out our Matrix channel
 [Gittyup:martix.org](https://matrix.to/#/#Gittyup:matrix.org).
 
+Multi language support
+======================
+
+Gittyup supports the following languages:
+- English (en)
+- German (de)
+- Spanisch (es)
+- Japanese (ja)
+- Portuguese (pt)
+- Portuguese Brazil (pt_BR)
+- Chinese (zh_CN)
+- Russian (ru)
+
+By default the system language is used. To switch to another language execute the application with the following command
+```
+LANG=<lang> <executable>
+```
+
+
 Features
 ========