[http-client-csharp] http/special-words cannot compile

[ArcturusZhang]

Another xml doc issue

        /// <summary> withCancellationToken. </summary>
        /// <param name="cancellationToken"></param>
        /// <param name="cancellationToken"> The cancellation token that can be used to cancel the operation. </param>
        /// <exception cref="ArgumentNullException"> <paramref name="cancellationToken"/> is null. </exception>
        /// <exception cref="ClientResultException"> Service returned a non-success status code. </exception>
        public virtual ClientResult WithCancellationToken(string cancellationToken, CancellationToken cancellationToken0 = default)

We have two cancellationToken in the xml doc.