More documentation (#10589)

packages/flutter_tools/lib/src/version.dart

diff --git a/packages/flutter_tools/lib/src/version.dart b/packages/flutter_tools/lib/src/version.dart
index 4246b61..de68f74 100644
--- a/packages/flutter_tools/lib/src/version.dart
+++ b/packages/flutter_tools/lib/src/version.dart
@@ -236,7 +236,7 @@
   /// This method sends a server request if it's been more than
   /// [kCheckAgeConsideredUpToDate] since the last version check.
   ///
-  /// Returns `null` if the cached version is out-of-date or missing, and we are
+  /// Returns null if the cached version is out-of-date or missing, and we are
   /// unable to reach the server to get the latest version.
   Future<DateTime> _getLatestAvailableFlutterVersion() async {
     Cache.checkLockAcquired();