Add known issues and limitations to INT doc

Change-Id: I01aa1c39b79585c3d250ed3c6c3628d487dd26a4
diff --git a/advanced/int.rst b/advanced/int.rst
index c0436b7..31f2fc2 100644
--- a/advanced/int.rst
+++ b/advanced/int.rst
@@ -296,4 +296,8 @@
      - UPF UPLINK RECIRC DENY
      - Missing rules for UE-to-UE communication.
 
+Known Issues and Limitations
+----------------------------
+
+ * Some INT collectors might not support dual-homed topology.