Merge pull request ethereum-optimism#902 from hash1go/main

Add Geth freezer feature callout for storage optimization

pages/builders/node-operators/tutorials/mainnet.mdx

@@ -35,6 +35,10 @@ Below are the storage needs as of April 2024:
 
 Based on these trends, node operators should plan for future storage needs and choose SSDs that can handle these increasing requirements.
 
+<Callout type="info">
+  Geth supports a "freezer" feature to store older chain data on HDDs, saving SSD space. Configure this for OP Mainnet using the `--datadir.ancient` flag. See [Geth docs](https://geth.ethereum.org/docs/fundamentals/databases) and [OP docs](https://docs.optimism.io/builders/node-operators/configuration/execution-config#datadirancient) for details.
+</Callout>
+
 ## Full Nodes
 
 ### Assess Blob Archiver