I have placed/laid large cement pavers (15 x 15 inch) under the doorway as this prevents anything digging under the door frame and provides a good surface for foot and wheelbarrow traffic.
Yes, the galvanised wire skirt (dog mesh) is tacked to the chicken wire mesh fence around the coop up about 1 or 2 feet then the excess is bent out from the base of the fence along the ground (on the outside of the pen) so the dog or fox can't dig under. Obviously, the mesh can't go across a doorway very easily so that's why I use large pavers.
This method works extremely well and I haven't had a breach of my pen in years since running this skirt around. Here's a video showing how I make my skirt
We did the same thing with our coup as far as bending the wire out along the ground so nothing could dig close to the pen. Ours is snake and rodent wire and I pegged anywhere it lifted off the ground so nothing could get in. The grass is growing through it and we can just mow straight over it. In many places where it's fully covered with grass you wouldn't even know there was wire there. Near the door, we just put more snake wire down it wraps around the bottom timber of the door and then comes out along the ground. Any corners have extra wire going across the overlaps so nothing can get under or did in