docs: document configuring wallet namespace

README.md

@@ -126,6 +126,28 @@ This will start an enclave named `op-devnet`. You can tear down the enclave with
 
 Consult the [Kurtosis OP package](https://github.com/ethpandaops/optimism-package) repository for instructions on how to adjust the args file to spin up additional services, like a block exporer.
 
+### Wallet extension
+
+Odyssey has a custom `wallet_` namespace, that allows users to delegate their EOAs to a contract using EIP-7702, and perform transactions on those accounts, all funded by the sequencer.
+
+To enable this namespace, set the environment variable `EXP1_SK` to a private key that will sign the transactions, and `EXP1_WHITELIST` to a comma-delimited list of checksummed addresses accounts are allowed to delegate to. The new RPC method, `wallet_sendTransaction`, will only sign transactions that either:
+
+1. Delegate accounts to one of the whitelisted addresses using EIP-7702, or
+1. Send transactions to an EIP-7702 EOA that is already delegated to a whitelisted address
+
+The `wallet_sendTransaction` endpoint accepts the same fields as `eth_sendTransaction`, with these notable exceptions:
+
+1. `nonce` must not be set, as this is managed by the node
+1. `value` must be unset or 0
+1. `from` must not be specified
+
+The following fields are ignored, as they are overwritten internally:
+
+1. `gasPrice` (and EIP-1559 gas related pricing fields)
+1. `gasLimit`
+
+To get the list of contracts that are whitelisted for `wallet_sendTransaction`, you can query `wallet_getCapabilities`.
+
 ### Security
 
 See [SECURITY.md](SECURITY.md).