Update `TextField.style` documentation for Material 3 (#135556)

fixes [TextField uses bodyLarge instead of titleMedium as the documentation says
](https://github.com/flutter/flutter/issues/135411)

packages/flutter/lib/src/material/input_decorator.dart

@@ -2903,7 +2903,6 @@ class InputDecoration {
   /// {@endtemplate}
   final TextStyle? errorStyle;
 
-
   /// The maximum number of lines the [errorText] can occupy.
   ///
   /// Defaults to null, which means that the [errorText] will be limited

packages/flutter/lib/src/material/text_field.dart

@@ -423,7 +423,12 @@ class TextField extends StatefulWidget {
   ///
   /// This text style is also used as the base style for the [decoration].
   ///
-  /// If null, defaults to the `titleMedium` text style from the current [Theme].
+  /// If null, [TextTheme.bodyLarge] will be used. When the text field is disabled,
+  /// [TextTheme.bodyLarge] with an opacity of 0.38 will be used instead.
+  ///
+  /// If null and [ThemeData.useMaterial3] is false, [TextTheme.titleMedium] will
+  /// be used. When the text field is disabled, [TextTheme.titleMedium] with
+  /// [ThemeData.disabledColor] will be used instead.
   final TextStyle? style;
 
   /// {@macro flutter.widgets.editableText.strutStyle}