swap params are not described in natspec + docs

[Yorkemartin]

swap params comments are inherited to the interface, but are defined originally as structs, thus the input params are difficult to find definitions for

    struct ExactInputSingleParams {
        address tokenIn;
        address tokenOut;
        uint24 fee;
        address recipient;
        uint256 deadline;
        uint256 amountIn;
        uint256 amountOutMinimum;
        uint160 sqrtPriceLimitX96;
    }