change "this" formatting

lib/util/extensions/datetime.dart

@@ -1,12 +1,12 @@
 import 'package:timeago/timeago.dart' as timeago;
 
 extension FancyTime on DateTime {
-  /// returns [this] time as a relative, human-readable string. In short format
+  /// returns `this` time as a relative, human-readable string. In short format
   String get fancyShort => timeago.format(this,
       locale: 'en_short',
       clock: DateTime.now().subtract(DateTime.now().timeZoneOffset));
 
-  /// returns [this] time as a relative, human-readable string
+  /// returns `this` time as a relative, human-readable string
   String get fancy => timeago.format(this,
       clock: DateTime.now().subtract(DateTime.now().timeZoneOffset));
 }