Add blank line after first sentence of doc comment for fontFamily (#103119)

Author: nilsreichardt

packages/flutter/lib/src/painting/text_style.dart

@@ -529,8 +529,9 @@ class TextStyle with Diagnosticable {
   /// specified in one place, it will dominate [color] in another.
   final Color? backgroundColor;
 
-  /// The name of the font to use when painting the text (e.g., Roboto). If the
-  /// font is defined in a package, this will be prefixed with
+  /// The name of the font to use when painting the text (e.g., Roboto).
+  ///
+  /// If the font is defined in a package, this will be prefixed with
   /// 'packages/package_name/' (e.g. 'packages/cool_fonts/Roboto'). The
   /// prefixing is done by the constructor when the `package` argument is
   /// provided.