Document System.Type.MakeGenericMethodParameter (#3639)

* Document System.Type.MakeGenericMethodParameter

* suggestions by mairaw

* Warning fix

Author: carlossanlop

xml/System/Type.xml

@@ -5599,7 +5599,7 @@ One of the elements in the <paramref name="types" /> array is <see langword="nul
 -or-
 
 A null reference (<see langword="Nothing" /> in Visual Basic), to use the <see cref="P:System.Type.DefaultBinder" />.</param>
-        <param name="callConvention">To be added.</param>
+        <param name="callConvention">The object that specifies the set of rules to use regarding the order and layout of arguments, how the return value is passed, what registers are used for arguments, and how the stack is cleaned up.</param>
         <param name="types">An array of <see cref="T:System.Type" /> objects representing the number, order, and type of the parameters for the method to get.
 
 -or-
@@ -13866,10 +13866,12 @@ If the value of this property is `true` for an array type, it can be used to cre
         <Parameter Name="position" Type="System.Int32" Index="0" FrameworkAlternate="netcore-2.1;netcore-2.2;netcore-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="position">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="position">The typed parameter position.</param>
+        <summary>Returns a signature type object that can be passed into the <c>Type[]</c> array parameter of a <see cref="Overload:System.Type.GetMethod" /> method to represent a generic parameter reference.</summary>
+        <returns>A signature type object that can be passed into the <c>Type[]</c> array parameter of a <see cref="Overload:System.Type.GetMethod" /> method to represent a generic parameter reference.</returns>
         <remarks>To be added.</remarks>
+        <exception cref="T:System.ArgumentOutOfRangeException">
+          <paramref name="position" /> is negative.</exception>
       </Docs>
     </Member>
     <Member MemberName="MakeGenericSignatureType">