Original text:
14. QUIC version 1 does not specify a version negotiation mechanism in <del> the base spec but I-D.draft-ietf-quic-version-negotiation proposes an extension.  This process assumes that the set of versions that a server supports is fixed.  This complicates the process for deploying new QUIC versions or disabling old versions when servers operate in clusters. A server that rolls out a new version of QUIC can do so in three stages.  Each stage is completed across all server instances before moving to the next stage. In the first stage of deployment, all server instances start accepting new connections with the new version.  The new version can be enabled progressively across a deployment, which allows for selective testing.  This is especially useful when the new version is compatible with an old version, because the new version is more likely to be used. While enabling the new version, servers do not advertise the new version in any Version Negotiation packets they send.  This prevents clients that receive a Version Negotiation packet from attempting to connect to server instances that might not have the new version enabled. During the initial deployment, some clients will have received Version Negotiation packets that indicate that the server does not support the new version.  Other clients might have successfully connected with the new version and so will believe that the server supports the new version.  Therefore, servers need to allow for this ambiguity when validating the negotiated version. The second stage of deployment commences once all server instances are able to accept new connections with the new version.  At this point, all servers can start sending the new version in Version Negotiation packets. During the second stage, the server still allows for the possibility that some clients believe the new version to be available and some do not.  This state will persist only for as long as any Version Negotiation packets take to be transmitted and responded to.  So the third stage can follow after a relatively short delay. The third stage completes the process by enabling authentication of the negotiated version with the assumption that the new version is fully available. The process for disabling an old version or rolling back the introduction of a new version uses the same process in reverse. Servers disable validation of the old version, stop sending the old version in Version Negotiation packets, then the old version is no longer accepted. </del>  15.

Reviewer comments:
From NAME review.
Not sure if this is the right approach. The whole point of this document is that we don't want the reader ask to read the spec in details but pre-digest the important bits for the reader.
I'm not going to lie down in the road over this, but maybe there's a middle ground? Instead of punting totally to the VN Draft, maybe we can specifically say that VN has a deployment template in that section?
Feel free to create a PR :-)
per discussion with NAME on 5 July, keep the new text but add a short but useful summary of version negotiation above it. I'll rework this PR.
This entire section appears to be a duplicate of section 5 of the version negotiation draft. I suggest the authors verify that the latter has all the relevant information, and then replace this section with a reference to the VN draft.

Revised text:
14. QUIC version 1 does not specify a version negotiation mechanism in  <ins> the base specification, but I-D.draft-ietf-quic-version-negotiation proposes an extension that provides compatible version negotiation. This approach uses a three-stage deployment mechanism, enabling progressive rollout and experimentation with multiple versions across a large server deployment.  In this approach, all servers in the deployment must accept connections using a new version (stage 1) before any server advertises it (stage 2), and authentication of the new version (stage 3) only proceeds after advertising of that version is completely deployed. See Section 5 of I-D.draft-ietf-quic-version-negotiation for details. </ins> 15.