RFC 3627 to Historic Status

This document moves RFC3627 (Use of /127 Prefix Length Between Routers Considered Harmful) to HISTORIC status to reflect the updated guidance contained in RFC6164 (Using 127-Bit IPv6 Prefixes on Inter- Router Links). While a standards track document already supersedes an informational document and therefore RFC6164 is the appropriate guidance to follow when the two documents are in conflict, this links the two documents so that it is clearer that the IETF has updated guidance on the matter.