Documentation error: Incorrect plugin name in "select on focus" example

[ishara11rathnayake]

Hi team,

In the documentation for the select_on_focus plugin example, the plugin is incorrectly referenced. The current example shows:
$("#select-on-focus").selectize({ plugins: ["restore_on_backspace"] });

However, it should be:
$("#select-on-focus").selectize({ plugins: ["select_on_focus"] });

This can be misleading for users trying to implement the plugin correctly. Would be great if this could be updated.

Thanks for the awesome work on Selectize!