Fix error in example for printing dates, clarify comments in general

README.md

 Intl
 ====
 
 This package provides internationalization and localization facilities,
 including message translation, plurals and genders, date/number formatting
 and parsing, and bidirectional text.
 
 ## General
 The most important library is [intl][intl_lib]. It defines the [Intl][Intl]
 class, with the default locale and methods for accessing most of the
@@ skipping 21 matching lines @@
 spawned from that operation, and that the argument to
 [withLocale][withLocale]
 will supercede the [defaultLocale][defaultLocale] while the operation
 is active. If you are using different locales within an application,
 the [withLocale][withLocale] operation may be preferable to setting
 [defaultLocale][defaultLocale].
 
       Intl.withLocale('fr', () => print(myLocalizedMessage());
 
 To specify the locale for an operation you can create a format object in
-a specific locale, or pass in the locale as a parameter to methods.
+a specific locale, pass in the locale as a parameter to methods, or
+set the default locale.
 
-      var format = new DateFormat.yMd("ar");
-      var dateString = format.format(new DateTime.now());
-      print(myMessage(dateString, locale: 'ar');
+```dart
+var format = new DateFormat.yMd("ar");
+var dateString = format.format(new DateTime.now());
+```
+
+or
+
+```dart
+print(myMessage(dateString, locale: 'ar');
+```
+          
+or
+
+```dart
+Intl.defaultLocale = "es"'
+new DateFormat.jm().format(new DateTime.now());
+```
 
 ## Initialization
 
 All the different types of locale data require an async initialization step
 to make
 sure the data is available. This reduces the size of the application by only
 loading the
 data that is actually required.
 
 Each different area of internationalization (messages, dates, numbers) requires
@@ skipping 240 matching lines @@
 [NumberFormat]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/intl/intl.NumberFormat
 [withLocale]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/intl/intl.Intl#id_withLocale
 [defaultLocale]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/intl/intl.Intl#id_defaultLocale
 [Intl.message]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/intl/intl.Intl#id_message
 [Intl.plural]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/intl/intl.Intl#id_plural
 [Intl.gender]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/intl/intl.Intl#id_gender
 [DateTime]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/dart:core.DateTime
 [BidiFormatter]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/intl/intl.BidiFormatter
 [BidiFormatter.RTL]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/intl/intl.BidiFormatter#id_BidiFormatter-RTL
 [BidiFormatter.LTR]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/intl/intl.BidiFormatter#id_BidiFormatter-LTR