Added (draft) doc for mobile translations + added 2 new source string…

[simondubrulle]

This is my first contribution and I wanted to start with something 'simple'. My goal is to further contribute to the translation of Ente photos. I am trying to understand that process which is not yet entirely clear to me, especially when it comes to which files must be (or do not need to be) generated.

Description

As a first (small) step, I have:

• created 2 new source strings ('collaboratorsSuccessfullyAdded' and 'viewersSuccessfullyAdded') that replace hardcoded text in the "add_a_participant" page.
• Created draft of a documentation for translations on mobile app (based on the doc for web app)

Tests

Tested on my Pixel 6a

Built with :

• Flutter 3.24.3
• JDK 17.0.2
• Gradle 7.2

Questions

• I have manually updated the l10n.dart file (using existing similar strings ) but I guess it should be automatically generated from the intl_en.arb file, correct? If so, is it something anyone can do and can we add the step in the doc?
• Should the other languages be updated as well in that commit, or will they only be updated via the Github Crowdin action ? Looking at the existing PR, it seems like they might need to be updated as well in the commit.

[CLAassistant]

All committers have signed the CLA.