Merge pull request #865 from richardgreg/rollup_sequencerhttp-step

docs: Add rollup.sequencerhttp to node operation docs

pages/builders/chain-operators/management/operations.mdx

@@ -155,6 +155,9 @@ If you do it this way, you won't have to wait until the transactions are written
     If you already have peer to peer synchronization, add the new node to the `--p2p.static` list so it can synchronize.
 
 ### Start `op-geth` (using the same command line you used on the initial node)
+<Callout type="warning">
+**Important:** Make sure to configure the `--rollup.sequencerhttp` flag to point to your sequencer node. This HTTP endpoint is crucial because `op-geth` will route `eth_sendRawTransaction` calls to this URL. The OP Stack does not currently have a public mempool, so configuring this is required if you want your node to support transaction submission.
+</Callout>
 
 ### Start `op-node` (using the same command line you used on the initial node)
 </Steps>