UDN-fix: removes content that didn't make GA

Author: JoeAldinger

modules/nw-udn-best-practices.adoc

@@ -28,6 +28,4 @@ Before setting up a `UserDefinedNetwork` (UDN) resource, users should consider t
 [IMPORTANT]
 ====
 For {product-title} 4.17 and later versions, clusters use `169.254.0.0/17` for IPv4 and `fd69::/112` for IPv6 as the default masquerade subnet. These ranges should also be avoided by users. For upgraded clusters, there is no change to the default masquerade subnet.
-====
-
-* When setting up primary networks, you might consider reviewing the support matrix for creating primary networks using the UDN resource and Network Attachment Definition (NAD). For more information on feature support, see the "Support matrix".
+====