Move model h controller under ibm/model_m (#21526)

keyboards/ibm/model_m/modelh/readme.md

@@ -7,13 +7,14 @@ This conversion kit allows you to replace your IBM Model M's original internal c
 * Keyboard Maintainer: [John Hawthorn](https://github.com/jhawthorn)
 * Hardware Supported: IBM Model M
 * Hardware Availability: [www.modelh.club](www.modelh.club)
+* How to [build your own controller](https://github.com/jberclaz/modelh)
 
 Make example for this keyboard (after setting up your build environment):
 
-    make modelh:default
+    make ibm/model_m/modelh:default
 
 Flashing example for this keyboard:
 
-    make modelh:default:flash
+    make ibm/model_m/modelh:default:flash
 
 See the [build environment setup](https://docs.qmk.fm/#/getting_started_build_tools) and the [make instructions](https://docs.qmk.fm/#/getting_started_make_guide) for more information. Brand new to QMK? Start with our [Complete Newbs Guide](https://docs.qmk.fm/#/newbs).