Revert "Fix AppBar's title doc (#82570)"

This reverts commit 3ae8fb25f63caf328187eece70cf6b026defb7a0.
diff --git a/packages/flutter/lib/src/material/app_bar.dart b/packages/flutter/lib/src/material/app_bar.dart
index 57174c5..f7cc1ba 100644
--- a/packages/flutter/lib/src/material/app_bar.dart
+++ b/packages/flutter/lib/src/material/app_bar.dart
@@ -287,7 +287,7 @@
   /// The primary widget displayed in the app bar.
   ///
   /// Becomes the middle component of the [NavigationToolbar] built by this widget.
-  ///
+  //.
   /// Typically a [Text] widget that contains a description of the current
   /// contents of the app.
   /// {@endtemplate}