docs: correct the description of ui.Collection#on
docs: correct the description of ui.Collection#on

I checked the code. Event handlers get only one parameter.
FernCreek/tinymce,danielpunkass/tinymce,danielpunkass/tinymce,TeamupCom/tinymce,leofeyer/tinymce,gencer/tinymce,gencer/tinymce,leofeyer/tinymce,tinymce/tinymce,danielpunkass/tinymce,TeamupCom/tinymce,tinymce/tinymce,FernCreek/tinymce,tinymce/tinymce,FernCreek/tinymce