Add CPI example to DEVELOP.md

Change-Id: I8f281779228d0bba11bbe5504ba4e9a68e2f52f6

DEVELOP.md

@@ -70,3 +70,7 @@ Once you're done, press Ctrl-C. Run `tilt down` to tear down the devnet.
 To Solana:
 
     kubectl exec solana-devnet-0 -c setup -- client post-message Bridge1p5gheXUvJ6jGWGeCsgPKgnE3YgdGKRVCMY9o 1 confirmed ffff
+
+To Solana as CPI instruction:
+
+    kubectl exec solana-devnet-0 -c setup -- client post-message --proxy CP1co2QMMoDPbsmV7PGcUTLFwyhgCgTXt25gLQ5LewE1 Bridge1p5gheXUvJ6jGWGeCsgPKgnE3YgdGKRVCMY9o 1 confirmed ffff