Fix #312513: Add Sicilian translation

Author: Jojo-Schmitz

build/ci/tx2s3/languages.json

@@ -53,6 +53,7 @@
     "pt_BR": "Português brasileiro",
     "ro": "Română",
     "ru": "Русский",
+    "scn": "Sicilianu",
     "sk": "Slovenčina",
     "sl": "Slovenščina",
     "sr": "Srpski",

share/locale/README.md

@@ -23,9 +23,6 @@ In [MuseScore source](https://github.com/musescore/MuseScore)
 * Add the share/locale/instruments_XX.ts file, see above
 * Add the share/locale/tours_XX.ts file, see above
 
-* Finally create a PR
-
+* Add the language in build/ci/tx2s3/languages.json
 
-In [txt2s3 source](https://github.com/musescore/tx2s3)
-------
-* Modify languages.json (and create a PR)
+* Finally create a PR