Document adding a new language

[ann0see]

The procedure for adding a new language to the App should be documented in TRANSLATING.md or similar.

We need someone:

1. To read the TRANSLATING.md file in the docs/ folder
2. Find spots where you add the following list items in the same style the guide was written
3. Open a PR with the proposed changes

Ideally you know the translation process and know about the documentation.

The following list can be used as base:

Jamulus Internationalization
ex) Adding Korean

Translator's

• kr.nsi
• installerlng.nsi
• translation_ko_KR.ts
• util.cpp

Dev team's

• resources.qrc
• Jamulus.pro
• translation_ko_KR.qm
• Jamulus Translator Organization

Originally posted by @bagjunggyu in #2741 (comment)

[ann0see]

We now also might add nb_NO so this gets more important.