added menu to contributing docs

CONTRIBUTING.md

@@ -9,13 +9,19 @@ Hedy is now available in Dutch, French, English and Spanish, but we'd love to su
 
 If you would like to add a translation, there a three places where files that need to be translated:
 
-1) In the folder [level-defaults](https://github.com/Felienne/hedy/blob/master/coursedata/level-defaults/) is a file for each language. That file controls what the landing page for each levels looks like. It is probably easiest to copy the [English file](https://github.com/Felienne/hedy/blob/master/coursedata/level-defaults/en.yaml), rename it and translate that. Tip: example variables can be translated too, that is probably helpful for learners!
+1) The folder [level-defaults](https://github.com/Felienne/hedy/blob/master/coursedata/level-defaults/) has a file for each language. That file controls what the landing page for each levels looks like. It is probably easiest to copy the [English file](https://github.com/Felienne/hedy/blob/master/coursedata/level-defaults/en.yaml), rename it and translate that. Tip: example variables can be translated too, that is probably helpful for learners!
 
 2) In the folder [texts](https://github.com/Felienne/hedy/tree/master/coursedata/texts) there is a file for each language too. That file translate UI-elements like menu headers, and, important, the error messages Hedy programmers will see. As above, copying the English file [English file](https://github.com/Felienne/hedy/blob/master/coursedata/texts/en.yaml) and translate that.
 
 3) The folder [main](https://github.com/Felienne/hedy/tree/master/main) controls the web pages around Hedy. [start](https://github.com/Felienne/hedy/blob/master/main/start-en.md) holds the content of the start page, and there is a page with press, and with contact info too. If you want to, you can skip those pages (people will then see the English version)
 
-Translated all of that? Then go to [app.py](https://github.com/Felienne/hedy/blob/master/app.py) and add your language to this list:
+Translated all of that? 
+
+Two more small things to do!
+
+1) Add your language to the [menu](https://github.com/Felienne/hedy/blob/master/main/menu.json).
+
+2) Now go to [app.py](https://github.com/Felienne/hedy/blob/master/app.py) and add your language to this list:
 
 ALL_LANGUAGES = {
     'en': '🇺🇸',