Add Dovetail Joint featurescript to the Manufacturing section

[Nico04]

Suggestion: Add "Dovetail Joint" to the Manufacturing section in docs/resources/featurescripts.md

The following entry could be added to the Manufacturing block:

• Dovetail Joint

  • Generates dovetail joints between parts for strong interlocking connections
  • Useful for 3D-printed assemblies

Reference: https://forum.onshape.com/discussion/30395/custom-feature-dovetail-joint/p1

(PS : I'm the author)