fix miniature definition

Closes #9101.

PiperOrigin-RevId: 262640267
diff --git a/site/docs/skylark/tutorial-creating-a-macro.md b/site/docs/skylark/tutorial-creating-a-macro.md
index cc75bf5..b241070 100644
--- a/site/docs/skylark/tutorial-creating-a-macro.md
+++ b/site/docs/skylark/tutorial-creating-a-macro.md
@@ -40,7 +40,7 @@
     name = name,
     srcs = [src],
     outs = ["small_" + src],
-    cmd = "convert $< -resize 100x100 $@",
+    cmd = "convert $< -resize " + size + " $@",
     **kwargs
   )
 ```