chore(doc, ui): minor formatting changes

Signed-off-by: Sahil Kumar <[email protected]>

docusaurus/docs/Flutter/guides/adding_localization.mdx

@@ -175,6 +175,6 @@ Example:
 	<string>nb</string>
 	<string>fr</string>
 	<string>it</string>
-  <string>es</string>
+	<string>es</string>
 </array>
 ```

packages/stream_chat_flutter/example/lib/main.dart

@@ -74,6 +74,7 @@ class MyApp extends StatelessWidget {
           Locale('hi'),
           Locale('fr'),
           Locale('it'),
+          Locale('es'),
         ],
         localizationsDelegates: GlobalStreamChatLocalizations.delegates,
         builder: (context, widget) => StreamChat(