finally commit the overly delayed RFC1812 admin prohibited option
diff --git a/INCOMPATIBILITIES b/INCOMPATIBILITIES
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+INCOMPATIBILITIES:
+
+- The REJECT target has an '--reject-with admin-prohib' option which used
+  with kernels that do not support it, will result in a plain DROP instead
+  of REJECT.  Use with caution.
+  Kernels that do support it: