docs: add stubs for all commands

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

docs/reference/buildx_version.md

@@ -0,0 +1,24 @@
+# buildx version
+
+```
+Usage:  docker buildx version
+
+Show buildx version information
+
+Options:
+      --builder string   Override the configured builder instance
+```
+
+## Description
+
+Show buildx version information
+
+## Examples
+
+### View version information
+
+
+```console
+$ docker buildx version
+github.com/docker/buildx v0.5.1-docker 11057da37336192bfc57d81e02359ba7ba848e4a
+```