added dark - light theme strings

Signed-off-by: Pranshul <pranshul.devmain@gmail.com>

app/src/main/assets/langs/languages.json

@@ -517,6 +517,9 @@
     "mins_sub_text": "mins",
     "loading_text": "Loading...",
     "edit_location_headline": "Edit location",
-    "edit_location_error_sub": "Please fill in the field or reset it"
+    "edit_location_error_sub": "Please fill in the field or reset it",
+    "app_theme_dark_light": "App theme",
+    "theme_dark": "Dark",
+    "theme_light": "Light"
 
-}
+}