Update CallingConvention.xml (dotnet#3967)

Author: jkotas

xml/System.Runtime.InteropServices/CallingConvention.xml

@@ -175,7 +175,7 @@
       </ReturnValue>
       <MemberValue>3</MemberValue>
       <Docs>
-        <summary>The callee cleans the stack. This is the default convention for calling unmanaged functions with platform invoke.</summary>
+        <summary>The callee cleans the stack.</summary>
       </Docs>
     </Member>
     <Member MemberName="ThisCall">
@@ -253,7 +253,7 @@
       </ReturnValue>
       <MemberValue>1</MemberValue>
       <Docs>
-        <summary>This member is not actually a calling convention, but instead uses the default platform calling convention. For example, on Windows the default is <see cref="F:System.Runtime.InteropServices.CallingConvention.StdCall" /> and on Windows CE.NET it is <see cref="F:System.Runtime.InteropServices.CallingConvention.Cdecl" />.</summary>
+        <summary>This member is not actually a calling convention, but instead uses the default platform calling convention. For example, on Windows x86 the default is <see cref="F:System.Runtime.InteropServices.CallingConvention.StdCall" /> and on Linux x86 it is <see cref="F:System.Runtime.InteropServices.CallingConvention.Cdecl" />.</summary>
       </Docs>
     </Member>
   </Members>