docs(contracts): added EigenLayer integration in README

bolt-contracts/README.md

@@ -48,11 +48,10 @@ coordination of validators, operators, and vaults within the Bolt network.
 
 Key features include:
 
-1. Registration of Symbiotic Operators and Vaults
+1. Registration of Symbiotic Operators and Vaults / EigenLayer Operators and Strategies
 2. Whitelisting of collateral assets used to back commitments
 3. Retrieval of operator stake and proposer status from their pubkey
-4. Integration with Symbiotic
-5. (WIP) Integration with Eigenlayer
+4. Integration with Symbiotic/EigenLayer
 
 ### Symbiotic Integration guide for Staking Pools
 
@@ -62,7 +61,7 @@ on how to spin up a Vault and start receiving stake from your node operators.
 
 Opting into Bolt works as any other Symbiotic middleware integration. Here are the steps:
 
-1. Make sure your vault collateral is whitelisted in `BoltManager` by calling `isCollateralWhitelisted`.
+1. Make sure your vault collateral is whitelisted in `BoltManager` by calling `isSymbioticCollateralWhitelisted`.
 2. Register as a vault in `BoltManager` by calling `registerSymbioticVault`.
 3. Verify that your vault is active in `BoltManager` by calling `isSymbioticVaultEnabled`.
 4. Set the network limit for your vault in Symbiotic with `Vault.delegator().setNetworkLimit()`.
@@ -83,9 +82,70 @@ The opt-in process requires the following steps:
 5. get approved by the vault.
 6. start providing commitments with the stake provided by the vault.
 
-### Eigenlayer Integration guides
-
-WIP
+### EigenLayer Integration Guide for Node Operators and Solo Stakers
+
+> [!NOTE]
+> Without loss of generality, we will assume the reader of this guide is a Node
+> Operator (NO), since the same steps apply to solo stakers.
+
+As a Node Operator you will be an ["Operator"](https://docs.eigenlayer.xyz/eigenlayer/overview/key-terms)
+in the Bolt AVS built on top of EigenLayer. This requires 
+running an Ethereum validator and the Bolt sidecar in order issue
+preconfirmations.
+
+The Operator will be represented by an Ethereum address that needs
+to follow the standard procedure outlined in the
+[EigenLayer documentation](https://docs.eigenlayer.xyz/) to opt into EigenLayer. Let's go through the steps:
+
+1. As an Operator, you register into EigenLayer using [`DelegationManager.registerAsOperator`](https://github.com/Layr-Labs/eigenlayer-contracts/blob/mainnet/src/contracts/core/DelegationManager.sol#L107-L119).
+
+2. As an Ethereum validator offering precofirmations a NO needs some collateral in
+   order to be economically credible. In order to do that, some entities known as a "stakers"
+   need to deposit whitelisted Liquid Staking Tokens (LSTs)
+   into an appropriate "Strategy" associated to the LST via the
+   [`StrategyManager.depositIntoStrategy`](https://github.com/Layr-Labs/eigenlayer-contracts/blob/mainnet/src/contracts/core/StrategyManager.sol#L105-L110),
+   so that the Operator has a `min_amount` (TBD) of collateral associated to it.
+   Whitelisted LSTs are exposed by the `BoltEigenLayerMiddleware` contract
+   in the `getWhitelistedCollaterals` function.
+   Note that NOs and stakers can be two different entities
+   _but there is fully trusted relationship as stakers will be slashed if a NO misbehaves_.
+
+3. After the stakers have deposited their collateral into a strategy they need
+   to choose you as their operator. To do that, they need to call the function
+   [`DelegationManager.delegateTo`](https://github.com/Layr-Labs/eigenlayer-contracts/blob/mainnet/src/contracts/core/DelegationManager.sol#L154-L163).
+
+4. As an Operator you finally opt into the Bolt AVS by interacting with the `BoltEigenLayerMiddleware`.
+   This consists in calling the function `BoltEigenLayerMiddleware.registerOperatorToAVS`.
+   The payload is a signature whose digest consists of:
+
+   1. your operator address
+   2. the `BoltEigenLayerMiddleware` contract address
+   3. a salt
+   4. an expiry 2.
+
+   The contract will then forward the call to the [`AVSDirectory.registerOperatorToAVS`](https://github.com/Layr-Labs/eigenlayer-contracts/blob/mainnet/src/contracts/core/AVSDirectory.sol#L64-L108)
+   with the `msg.sender` set to the Bolt AVS contract. Upon successful verification of the signature,
+   the operator is considered `REGISTERED` in a mapping `avsOperatorStatus[msg.sender][operator]`.
+
+Lastly, a NO needs to interact with both the `BoltValidators` and `BoltEigenLayerMiddleware`
+contract. This is needed for internal functioning of the AVS and to make RPCs aware that you are a
+registered operator and so that they can forward you preconfirmation requests.
+
+The steps required are the following:
+
+1. Register all the validator public keys you want to use with Bolt via the `BoltValidators.registerValidator`.
+   If you own more than one validator public key,
+   you can use the more gas-efficient `BoltValidators.batchRegisterValidators` function.
+   The `authorizedOperator` argument must be the same Ethereum address used for
+   opting into EigenLayer as an Operator.
+
+2. Register the same Operator address in the `BoltEigenLayerMiddleware` contract by calling
+   the `BoltEigenLayerMiddleware.registerOperator` function. This formalizes your role within the Bolt network
+   and allows you to manage operations effectively, such as pausing or resuming
+   your service.
+
+3. Register the EigenLayer strategy you are using for restaking _if it has not been done by someone else already_.
+   This ensures that your restaked assets are correctly integrated with Bolt’s system.
 
 ## Fault Proof Challenge and Slashing: `BoltChallenger`