UWP Xbox One Options - Language

Hello,

I am trying to edit the Xbox One Language panel in Options in order to add a couple of languages my game supports, right below the

Code:

<!-- Add languages you support here -->
 <!-- os_get_language will only return languages listed -->
 <!-- "en" is supported by default -->
 <!-- See "NLS APIs and Localization" white paper -->
 <!-- from developer.xboxlive.com for info -->

area.
I have consulted the relevant parer by Microsoft but I still haven't made the project compile.

What i have tried:

1.

Code:

<Resources>
    <Resource Language="fr-FR"/>
    <Resource Language="de-DE"/>
</Resources>

2.

Code:

<fr-FR>
<de-DE>

3.

Code:

fr-FR
de-DE

I'm a total noob as far as Xbox One development goes, can someone provide an example as to what I am supposed to write in that area?