Improve Acre contract docs comment

Add short description what is the purpose of Acre system.

core/contracts/Acre.sol

@@ -4,12 +4,16 @@ pragma solidity ^0.8.21;
 import "@openzeppelin/contracts/token/ERC20/extensions/ERC4626.sol";
 
 /// @title Acre
-/// @notice Implementation of the ERR-4626 tokenized vault standard. ERC-4626 is
-///         a standard to optimize and unify the technical parameters of
-///         yield-bearing vaults. This contract allows the minting and burning
-///         of shares, represented as standard ERC20 token, in exchange for tBTC
-///         tokens.
-/// @dev ERC-4626 standard extends the ERC-20 token.
+/// @notice This contract implements the ERC-4626 tokenized vault standard. By
+///         staking tBTC, users acquire a liquid staking token called stBTC,
+///         commonly referred to as "shares". The staked tBTC is securely
+///         deposited into Acre's vaults, where it generates yield over time.
+///         Users have the flexibility to redeem stBTC, enabling them to
+///         withdraw their staked tBTC along with the accrued yield.
+/// @dev ERC-4626 is a standard to optimize and unify the technical parameters
+///      of yield-bearing vaults. This contract facilitates the minting and
+///      burning of shares (stBTC), which are represented as standard ERC20
+///      tokens, providing a seamless exchange with tBTC tokens.
 contract Acre is ERC4626 {
     event StakeReferral(bytes32 indexed referral, uint256 assets);