Clarify how to set ComVisible for Ribbon

Author: govert

Ribbon/Readme.md

@@ -74,7 +74,7 @@ namespace Ribbon
 
 * The ribbon class derives from the `ExcelDna.Integration.CustomUI.ExcelRibbon` base class. This is how Excel-DNA itentifies the class a defining a ribbon controller.
 
-* The ribbon class must be 'COM visible'. Either the class must be marked as `[ComVisible(true)]` (the default class library template in Visual Studio markes the assembly as `[assembly:ComVisible(false)]`).
+* The ribbon class must be 'COM visible'. To ensure this, either the methods must be marked `[ComVisible(true)]`, or the assembly must be marked as `[assembly:ComVisible(true)]` instead of `[assembly:ComVisible(false)]` in the AssemblyInfo.cs file, or the attribute on the assembly of `[assembly:ComVisible(false)]` that is added by the default project templates must be removed, reverting to the default state (where the ComVisible state for the assembly is true).
 
 * The xml namespace is important. Excel 2007 introduced the ribbon, and support only the original xml namespace as shown in this example - `xmlns='http://schemas.microsoft.com/office/2006/01/customui'`. Further enhancements to the ribbon was made in Excel 2010, including using the ribbon for worksheet context menus and adding the backstage area. To indicate the extended Excel 2010 xml schema, this version and later supports an update namespace - `xmlns='http://schemas.microsoft.com/office/2009/07/customui'`.