Remix of Anet A8 y-belt-holder

**Remix of anet A8 y-belt-holder by JackTheQuila**

The files proposed by JackTheQuila were really too tight to insert the belt of my Anet A8.

1) So, we took the ratings of Sjouke's great work on his [Anet A8 prusa-i3 X-belt holder](https://www.thingiverse.com/thing:1685768), to merge with this piece.
2) In addition, the angle of the "gutter" does not seem useful, we returned to a straight line, to facilitate the insertion of the belt.

This remix was created by [zapyloop](https://www.t