Hotend chain mount

I modified the hotend mount so that it aligns with the cable guide of the [Satsana Duct](https://www.thingiverse.com/thing:4623647) on my ender 3 v2.
My printer also uses a [cleaning brush mod](https://www.thingiverse.com/thing:4564295), so this version allows the hotend to move till the end of the rail.