Add warning about multichain contract submission team requirements (#762)

Co-authored-by: Cursor Agent <[email protected]>

Author: karimhass

web-app/decoding/multichain-decoding.mdx

@@ -183,6 +183,10 @@ This standardized labeling enables Dune to merge data from different chains into
 
 ### Submitting Multichain Contracts
 
+<Warning>
+**Paid Team Required**: Only users with a paid team subscription can submit multichain contracts. Individual accounts and free teams do not have access to multichain contract submissions. For more information about team plans, see our [pricing page](https://dune.com/pricing).
+</Warning>
+
 <div
   style={{
     position: "relative",