update gitignore

Author: hukusuke1007

flamingo/.gitignore

@@ -26,4 +26,5 @@ doc/api/
 .idea/*
 !.idea/codeStyleSettings.xml
 !.idea/codeStyles/*
-!.idea/vcs.xml
+!.idea/vcs.xml
+

flamingo/example/.gitignore

@@ -72,4 +72,8 @@
 !**/ios/**/default.perspectivev3
 !/packages/flutter_tools/test/data/dart_dependencies_test/**/.packages
 
-.flutter-plugins-dependencies
+.flutter-plugins-dependencies
+
+android/app/google-services.json
+ios/Runner/GoogleService-Info.plist
+web/index.html