Document *args and **kwargs restriction in BUILD files

RELNOTES: None.
PiperOrigin-RevId: 233424402
diff --git a/site/docs/build-ref.html b/site/docs/build-ref.html
index d4a2e29..d4ec6ec 100644
--- a/site/docs/build-ref.html
+++ b/site/docs/build-ref.html
@@ -459,7 +459,9 @@
   contain function definitions, <code>for</code> statements or
   <code>if</code> statements (but list comprehensions and <code>if</code>
   expressions are allowed). Functions should be declared in <code>.bzl</code>
-  files instead.
+  files instead. Additionally, <code>*args</code> and <code>**kwargs</code>
+  arguments are not allowed in BUILD files; instead list all the arguments
+  explicitly.
 </p>
 
 <p>