The example for CheckSignature(X509Certificate2Collection, Boolean) in the System.Security.Cryptography.Pkcs/SignedCms.xml section uses the same code as the previous method (CheckSignature(Boolean))
The examples for both methods link to ~/samples/snippets/csharp/VS_Snippets_WindowsServer/mpkcs_SignedCMS/cs/Program.cs#1) which is an example for CheckSignature(Boolean). There does not appear to be an example for CheckSignature(X509Certificate2Collection, Boolean) in the samples repo.

I think the fix is to first add the example to the samples repo, then point this documentation to that sample