fix: added readme for manual message claiming

src/contracts/adapters/linea/README.md

@@ -0,0 +1,26 @@
+# Manual Message Claiming
+
+To manually claim a message sent from origin (Ethereum) on the Linea network follow these steps:
+
+1. Get the tx hash where the message was sent on the origin network (Ethereum). This is to get all the information
+needed on the following steps. Once you have the tx hash, go to the block explorer, input the tx hash, and then go to events.
+Once you are on the events page of the tx, locate the event `MessageSent`
+2. Go to the online event decode page: https://tools.deth.net/event-decoder and input the event topics from step 1, and the data.
+Add this code (event abi) to the ABI text box:
+```
+event MessageSent(
+    address indexed _from,
+    address indexed _to,
+    uint256 _fee,
+    uint256 _value,
+    uint256 _nonce,
+    bytes _calldata,
+    bytes32 indexed _messageHash
+  );
+```
+3. Go to the Linea block explorer: https://lineascan.build/ and add the Linea MessageService contract:
+- mainnet: [0x508Ca82Df566dCD1B0DE8296e70a96332cD644ec](https://sepolia.lineascan.build/address/0x508Ca82Df566dCD1B0DE8296e70a96332cD644ec#writeProxyContract)
+- sepolia: [0x971e727e956690b9957be6d51Ec16E73AcAC83A7](https://sepolia.lineascan.build/address/0x971e727e956690b9957be6d51Ec16E73AcAC83A7#writeProxyContract)
+Once there go to write as proxy contract, and fill the information from step 2 to the method `claimMessage` and execute the tx.
+Take into account that the topics, calldata and nonce must be in Hex format.
+