Corrected mistake/typo on return value

Corrected mistake/typo on the return value, as according to https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v4.8.2/contracts/utils/math/SafeCast.sol#L847

content/3. Solidity 201/OZ SafeCast.md

@@ -3,7 +3,7 @@ OpenZeppelin SafeCast: Wrappers over Solidity's uintXX/intXX casting operators w
 
 1. `toUint128(uint256 value) returns (uint128)`: Returns the downcasted `uint128` from `uint256`, reverting on overflow (when the input is greater than largest `uint128`). Similar functions are available for `toUint64(uint256 value)`, `toUint32(uint256 value)`, `toUint16(uint256 value)`, `toUint8(uint256 value)`
 
-2. `toInt128(int256 value) internal pure returns (uint256)`: Returns the downcasted int128 from `int256`, reverting on overflow (when the input is less than smallest `int128` or greater than largest `int128`). Similar functions are available for `toInt64(int256 value)`, `toInt32(int256 value)`, `toInt16(int256 value)`, `toInt8(int256 value)`.
+2. `toInt128(int256 value) internal pure returns (int256)`: Returns the downcasted int128 from `int256`, reverting on overflow (when the input is less than smallest `int128` or greater than largest `int128`). Similar functions are available for `toInt64(int256 value)`, `toInt32(int256 value)`, `toInt16(int256 value)`, `toInt8(int256 value)`.
 
 3. `function toInt256(uint256 value) returns (int256)`: Converts an unsigned `uint256` into a signed `int256`
 
@@ -24,4 +24,4 @@ ___
 ## References
 - [Youtube Reference](https://youtu.be/L_9Fk6HRwpU?t=964)
 ___
-## Tags
+## Tags