Update draft-ietf-idr-ls-distribution.xml

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Merge pull request #2 from balaji-rajagopalan/patch-1

incorporate inter-ASBR comments from balaji - it is perfectly letigimate to use "passive' links as inter-ASBR link. therefor the protocol code will be set to 'OSPF, ISIS-L1 or ISIS-L2' and not just 'static' or 'direct'