Update gitignore

example/.gitignore

@@ -22,6 +22,7 @@
 
 # Flutter/Dart/Pub related
 **/doc/api/
+**/ios/Flutter/.last_build_id
 .dart_tool/
 .flutter-plugins
 .flutter-plugins-dependencies
@@ -30,6 +31,15 @@
 .pub/
 /build/
 
+# Web related
+lib/generated_plugin_registrant.dart
+
+# Symbolication related
+app.*.symbols
+
+# Obfuscation related
+app.*.map.json
+
 # Android related
 **/android/**/gradle-wrapper.jar
 **/android/.gradle