Update create-l2-rollup.mdx

Author: opfocus

pages/builders/chain-operators/tutorials/create-l2-rollup.mdx

@@ -697,7 +697,7 @@ cd ~/optimism/op-proposer
 ./bin/op-proposer \
   --poll-interval=12s \
   --rpc.port=8560 \
-  --rollup-rpc=http://localhost:8547 \
+  --rollup-rpc=http://localhost:9545 \
   --l2oo-address=$(cat ../packages/contracts-bedrock/deployments/getting-started/.deploy | jq -r .L2OutputOracleProxy) \
   --private-key=$GS_PROPOSER_PRIVATE_KEY \
   --l1-eth-rpc=$L1_RPC_URL