docs: add localization section to new CONTRIBUTING.md

CONTRIBUTING.md

@@ -0,0 +1,10 @@
+# Contributing
+
+## Localization
+
+In order to improve or add support for a language, please follow these steps:
+
+- Localized strings can be found in two different places:
+  - The `app_XX.arb` file located in [`lib/l10n`](lib/l10n) (where `XX` corresponds to the language code), that contains the vast majority of all strings. Please make sure that you do not localize any parameter name (ex: `{parameter}`) and that you do escape single quotes (ex: `I''m ok` instead of `I'm ok`).
+  - The [`harcoded_localizations.dart`](lib/l10n/harcoded_localizations.dart), that contains a few specific strings that need to be hardcoded.
+- Localized strings can be generated with the `flutter gen-l10n` command. Check that the [`unstranslated.txt`](lib/l10n/untranslated.txt) file is empty, otherwise it will indicate which strings you did not translate.

README.md

@@ -72,7 +72,7 @@ See more screenshots [here](assets/screenshots).
 - French
 - Turkish
 
-To improve or add a language, please see [CONTRIBUTING.md](CONTRIBUTING.md).
+To improve or add support for a language, please see [CONTRIBUTING.md](CONTRIBUTING.md#localization).
 
 ## Credits
 

lib/l10n/harcoded_localizations.dart

@@ -10,7 +10,7 @@ import 'package:localmaterialnotes/utils/locale_manager.dart';
 /// App name.
 const _appName = 'Material Notes';
 
-/// List of supported localizations.
+/// All supported localizations.
 enum SupportedLocalizations {
   english(Locale('en')),
   french(Locale('fr')),