docs(itero): add the event so users can remap it (#1425)

lua/neorg/modules/core/itero/module.lua

@@ -8,7 +8,8 @@
 `core.itero` is a rather small and simple module designed to assist in the creation of many lists,
 headings and other repeatable (iterable) items.
 
-By default, the key that is used to iterate on an item is `<M-CR>` (Alt + Enter).
+By default, the key that is used to iterate on an item is `<M-CR>` (Alt + Enter). If you want to
+change the bind, remap the `core.itero.next-iteration` event.
 
 Begin by writing an initial item you'd like to iterate (in this instance, and unordered list item):
 ```md