Update README.md

Author: sco1

CAD/README.md

@@ -5,4 +5,6 @@ Also viewable on [MakerWorld](https://makerworld.com/en/models/410275)
 
 A 3D printable mount for the SkyPortal, compatible with the original PyPortal form factor. The PyPortal is mounted to the mounting plate using M2.5 x 4mm screws (4x),  M2.5 x 6mm screws (4x), and M2.5 x 6mm standoffs (4x).
 
+**NOTE:** No tolerance has been built in for fitting of components. The mounting plate and/or base plate channel may need to be toleranced at print time or sanded post-print for fitment prior to assembly.
+
 ![assembly-exploded](./assembly.png)