Documentation website links / search / description

This one will probably need to be broken down to multiple issues. So please bear with me:

Landing on the [class Helper](https://api.emberjs.com/ember/3.13/classes/Helper/methods) page this morning I noticed that although the example uses `format-currency` helper name, the code block for that helper says only `currency.js`


So I thought I would help by clicking on the "edit" button and issuing PR directly from [Github editor](https://github.com/emberjs/ember.js/edit/release/packages/@ember/-internals/glimmer/lib/helper.ts#L46).

But the code block there reads (at line 64): `app/helpers/format-currency.js`, so now I'm not sure whether:
a) I'm looking at different *branch* of the github repo. In which case the edit button is wrong to taking me to branch *release*.
b) The branch *release* is actually correct for this case, but the component that displays the code snippet has a bug that trims `app/helpers/format-currency.js` to `currency.js`?

Right after that I noticed that down below in the code there is a mention about "helper function":
> In many cases, the ceremony of a full `Helper` class is not required.

Never saw that. So I tried to go back to guides page and search for it, but no results:

[But the page for helper as function](http://api.emberjs.com/ember/3.13/functions/@ember%2Fcomponent%2Fhelper/helper) (when I crafter the URL manually) does exist.

So I went to see the respective item in the side menu on that page. The item is not there: