Natspec type error in `_getProxyImplementation()` function inside the contract PoolAddressesProvider

[MatinR1]

The natspec of the function _getProxyImplementation() inside the contract PoolAddressesProvider has an extra [the](https://github.com/aave/aave-v3-core/blob/master/contracts/protocol/configuration/PoolAddressesProvider.sol#L194) between Returnsandimplementation`:

• @notice Returns the the implementation contract of the proxy contract by its identifier.

Consider removing one of the thes.