docs(readme): add instructions of out-of-band transaction signing

README.md

@@ -96,10 +96,45 @@ killall safenode || true && RUST_LOG=safenode,safe cargo run --bin testnet -- --
   `cargo run --release --bin safe -- wallet address`
 
 - Send tokens to an address, this will output a Transfer hex string that you must send to the recipient out-of-band
-  `cargo run --release --bin safe -- wallet send [amount] [address]`
+  `cargo run --release --bin safe -- wallet send <amount> <address>`
 
 - Receive tokens from a Transfer hex string
-  `cargo run --release --bin safe -- wallet receive [transfer]`
+  `cargo run --release --bin safe -- wallet receive <transfer>`
+
+### Out of band transaction signing
+
+Steps on the online device/computer:
+1. Create a watch-only wallet using the hex-encoded public key:
+  `cargo run --release --bin safe -- wowallet create <hex-encoded public key>`
+
+2. Deposit a cash-note, owned by the public key used above when creating, into the watch-only wallet:
+  `cargo run --release --bin safe -- wowallet deposit <hex-encoded public key> --cash-note <hex-encoded cash-note>`
+
+3. Build an unsigned transaction:
+  `cargo run --release --bin safe -- wowallet transaction <hex-encoded public key> <amount> <recipient's hex-encoded public key>`
+
+4. Copy the built unsigned Tx generated by the above command, and send it out-of-band to the desired device where the hot-wallet can be loaded.
+
+Steps on the offline device/computer:
+
+5. If you still don't have a hot-wallet created, which owns the cash-notes used to build the unsigned transaction, create it with the corresponding secret key: 
+  `cargo run --release --bin safe -- wallet create <hex-encoded secret key>`
+
+6. Use the hot-wallet to sign the built transaction:
+  `cargo run --release --bin safe -- wallet sign <unsigned transaction>`
+
+7. Copy the signed Tx generated by the above command, and send it out-of-band back to the online device.
+
+Steps on the online device/computer:
+
+8. Broadcast the signed transaction to the network using the watch-only wallet:
+  `cargo run --release --bin safe -- wowallet broadcast <signed transaction>`
+
+9. Deposit the change cash-note to the watch-only wallet:
+  `cargo run --release --bin safe -- wowallet deposit <hex-encoded public key> <change cash-note>`
+
+10. Send/share the output cash-note generated by the above command at step #8 to/with the recipient.
+
 
 ## Auditing