move spaceholdings boards into /spaceholdings (#16096)

keyboards/spaceholdings/nebula12/readme.md

@@ -12,7 +12,7 @@ This is a standard fixed layout 12 key PCB. It supports VIA, full per-key RGB an
 
 Make example for this keyboard (after setting up your build environment):
 
-    make nebula12:via
+    make spaceholdings/nebula12:via
 
 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).
 

keyboards/spaceholdings/nebula68/readme.md

@@ -12,7 +12,7 @@ This is a standard fixed layout 68% PCB. It supports VIA, full per-key RGB and u
 
 Make example for this keyboard (after setting up your build environment):
 
-    make nebula68:via
+    make spaceholdings/nebula68:via
 
 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).
 

keyboards/spaceholdings/nebula68b/readme.md

@@ -12,7 +12,7 @@ This is a standard fixed layout 68% PCB. It supports VIA, full per-key RGB and u
 
 Make example for this keyboard (after setting up your build environment):
 
-    make nebula68b:via
+    make spaceholdings/nebula68b:via
 
 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).