i18n [nfc]: Explain why we skip translating licenses

Signed-off-by: Zixuan James Li <[email protected]>

Author: PIG208

lib/licenses.dart

@@ -23,6 +23,12 @@ Stream<LicenseEntry> additionalLicenses() async* {
         rootBundle.loadString('assets/Pygments/AUTHORS.txt'),
       ]);
 
+      // This does not need to be translated, as it is just a small fragment
+      // of text surrounded by a large quantity of English text that isn't
+      // translated anyway.
+      // (And it would be logistically tricky to translate, as this code is
+      // called from the `main` function before the [ZulipApp] widget is built,
+      // let alone has updated [GlobalLocalizations].)
       return '$licenseFileText\n\nAUTHORS file follows:\n\n$authorsFileText';
     }());
   yield LicenseEntryWithLineBreaks(