FIXUP: Add battery compartment

Readme.md

@@ -120,6 +120,12 @@ The unit tests in this project are meant to be run on the host:
 cargo test --target host-tuple --bin test --no-default-features -F std,spat
 ```
 
+## PCB and Housing
+A simple PCB to combine the u-blox SAM-M10Q, a XIAO ESP32-C5 and the screen can be found in [hardware/c_its-companion/](./hardware/c_its-companion/) including finished gerber files.
+
+The housing is a FreeCAD model at [hardware/housing/c_its-companion-housing.FCStd](./hardware/housing/c_its-companion-housing.FCStd), but the same folder also contains finished 3mf models that can be loaded into a 3D printer slicer.
+The export is prepared for a 40x60x9mm lipo battery, e.g. LP803860 (2000 mAh) or no additional space below the PCB besides for the display standoffs.
+
 ## Tips and Tricks
 
 ### Create TGA Assets