Fix typo and replace "which" by "that" (#1236)

Author: LucasMetal

lib/PuppeteerSharp/Page.cs

@@ -1576,15 +1576,15 @@ void responseEventListener(object sender, ResponseCreatedEventArgs e)
         /// <summary>
         /// Navigate to the previous page in history.
         /// </summary>
-        /// <returns>Task which which resolves to the main resource response. In case of multiple redirects, 
+        /// <returns>Task that resolves to the main resource response. In case of multiple redirects, 
         /// the navigation will resolve with the response of the last redirect. If can not go back, resolves to null.</returns>
         /// <param name="options">Navigation parameters.</param>
         public Task<Response> GoBackAsync(NavigationOptions options = null) => GoAsync(-1, options);
 
         /// <summary>
         /// Navigate to the next page in history.
         /// </summary>
-        /// <returns>Task which which resolves to the main resource response. In case of multiple redirects, 
+        /// <returns>Task that resolves to the main resource response. In case of multiple redirects, 
         /// the navigation will resolve with the response of the last redirect. If can not go forward, resolves to null.</returns>
         /// <param name="options">Navigation parameters.</param>
         public Task<Response> GoForwardAsync(NavigationOptions options = null) => GoAsync(1, options);