Update and add Codeblock

Co-authored-by: Dr-Electron <[email protected]>

docs/content/developer/advanced/custom-indexer.mdx

@@ -32,8 +32,8 @@ Data ingestion for your indexer supports several checkpoint stream sources.
 
 The most straightforward stream source is to subscribe to a remote store of checkpoint contents. IOTA provides the following buckets:
 
-- Testnet: <code>{Networks.iota_move_testnet.indexerRpc}</code>
-- Devnet: <code>{Networks.iota_move_devnet.indexerRpc}</code> 
+- Testnet: <CodeBlock>{Networks.iota_move_testnet.indexerRpc}</CodeBlock>
+- Devnet: <CodeBlock>{Networks.iota_move_devnet.indexerRpc}</CodeBlock> 
 
 The checkpoint files are stored in the following format: <code>{Networks.iota_move_testnet.indexerRpc+`/<checkpoint_id>.chk`}</code>. You can download the checkpoint file by sending an HTTP GET request to the relevant URL. Try it yourself for checkpoint 1 at [{Networks.iota_move_testnet.indexerRpc}/1.chk](https://indexer.testnet.iota.cafe/1.chk).