Add a separate gitignore for `_examples`
Add a separate gitignore for `_examples`

SpineEventEngine/SpineEventEngine.github.io,SpineEventEngine/SpineEventEngine.github.io,SpineEventEngine/SpineEventEngine.github.io,SpineEventEngine/SpineEventEngine.github.io,SpineEventEngine/SpineEventEngine.github.io,SpineEventEngine/SpineEventEngine.github.io