[rbridge] Consensus Check: Pseudonode suppression

[Eastlake III Donald-LDE008]

This is a check via the mailing list to confirm or refute an apparent
consensus at the Vancouver meeting taken from the minutes of that
meeting:

   Move the Pseudonode suppression provisions
      out of the TRILL base protocol specification into a document
      closer to IS-IS.

If no particular controversy arises over this in the next three weeks,
We will declare it to be the working group consensus.

Thanks,
Donald & Erik