Added PixiLang as an example

src/SampleExtension/Localization/pixiLang.json

@@ -0,0 +1,3 @@
+{
+  "NEW_FILE": "New PixiFile"
+}

src/SampleExtension/extension.json

@@ -9,6 +9,11 @@
         "name": "English",
         "code": "en",
         "localeFileName": "Localization/en.json"
+      },
+      {
+        "name": "PixiLang",
+        "code": "px",
+        "localeFileName": "Localization/pixiLang.json"
       }
     ]
   },