Clarify naming.

README.md

@@ -8,12 +8,16 @@ license.
 
 Designed in OpenSCAD. It is paramaterized.
 
+Filenames:
+- `vulpes_v01` board version number
+- `headers` for board assembled with headers
+
 Related:
 - [ESP32-based radio controller for radio orienteering/ARDF](https://amiok.net/gitea/W1CDN/vulpes)
 - [Vulpes Radio Orienteering Controller](https://w1cdn.net/projects/vulpes-radio-orienteering-controller/)
 
-![Alt text](docs/vulpes_box_openscad.png "OpenSCAD")
+![Alt text](docs/vulpes_v01_box_headers_openscad.png "OpenSCAD")
 
-![Photo of 3d-printed box with PCB held in a slot.](docs/vulpes_box_photo_front_open.jpg "PCB in place")
+![Photo of 3d-printed box with PCB held in a slot.](docs/vulpes_v01_box_headers_photo_front_open.jpg "PCB in place")
 
-![Photo of same box, with cover on and all openings lined up.](docs/vulpes_box_photo_front.jpg "Cover in place")
+![Photo of same box, with cover on and all openings lined up.](docs/vulpes_v01_box_headers_photo_front.jpg "Cover in place")