docs(website): add node-troubleshooting for "Proposing operation erro…

…r" (#14336)

Co-authored-by: d1onys1us <[email protected]>

packages/website/pages/docs/reference/node-troubleshooting.mdx

@@ -6,6 +6,10 @@ You can ignore any WARN logs.
 
 ### Node error logs
 
+#### `error: "failed to check token balance: proposer does not have enough tko balance to propose"`
+
+You have not deposited enough TKO to pay the block fee. Deposit enough TKO from TKO token contracts. See [enable a proposer](/docs/guides/run-a-node/enable-a-proposer) for more info.
+
 #### `error: "failed to insert new head to L2 execution engine: missing trie node"`
 
 Make sure that your RPC is pointing to an Sepolia archive node, and not a full node.