Update UdapCertificationsAndEndorsementBuilder.cs

wip: tos was incorrectly set.  Yes I know there isn't a test for this.  There are so many test to still write for certifications and endorsements as there are a lot of rules.

Udap.Model/Registration/UdapCertificationsAndEndorsementBuilder.cs

@@ -351,7 +351,7 @@ public UdapCertificationsAndEndorsementBuilder WithLogoUri(string logoUri)
  /// <returns></returns>
  public UdapCertificationsAndEndorsementBuilder WithTermsOfService(string termsOfService)
  {
- _document.ClientUri = termsOfService;
+ _document.TosUri = termsOfService;
  return this;
  }