How to config CKEditor-4 inline editors?

How to config CKEditor-4 inline editors?

I have a standard installation (like samples):
<meta charset="utf-8"></meta>
<script src="../ckeditor.js"></script>
With HTML content with many <div contenteditable="true"> blocks. I need to
configure each editor by an external configX.js file,
<script>
CKEDITOR.on( 'instanceCreated', function( event ) {
var editor = event.editor, element = editor.element;
if ( element.is( 'h1', 'h2', 'h3' ) ) {
// WHERE PUT THIS ITEM?
customConfig: '/custom/ckconfigType1.js';
} else {
// WHERE PUT THIS ITEM?
customConfig: '/custom/ckconfigType2.js';
}
});
</script>
So, my problem is
How to do a customConfig in this context?
Where the "best complete documentation", about config menus
(editor.config.toolbarGroups) without online configuration-tool, where I
can understand how to put and remove menu itens with correct names?