Fix typo in ProductInfoHeaderValue.xml (#3363)

Author: f00f

xml/System.Net.Http.Headers/ProductInfoHeaderValue.xml

@@ -77,7 +77,7 @@
         <Parameter Name="product" Type="System.Net.Http.Headers.ProductHeaderValue" />
       </Parameters>
       <Docs>
-        <param name="product">A <see cref="T:System.Net.Http.Headers.ProductInfoHeaderValue" /> object used to initialize the new instance.</param>
+        <param name="product">A <see cref="T:System.Net.Http.Headers.ProductHeaderValue" /> object used to initialize the new instance.</param>
         <summary>Initializes a new instance of the <see cref="T:System.Net.Http.Headers.ProductInfoHeaderValue" /> class.</summary>
         <remarks>To be added.</remarks>
       </Docs>