doc: remove confusing reference in governance doc

At the CTC meeting today, Sakthipriyan noted that there was a link to
the CTC consensus material from the pull request consensus material. The
link was confusing because the CTC consensus material is
meeting-specific, which does not apply to pull requests. I have removed
that link and replaced it with a text explanation.

PR-URL: https://github.com/nodejs/node/pull/9073
Reviewed-By: Myles Borins <myles.borins@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

GOVERNANCE.md

@@ -36,10 +36,17 @@ Collaborators. All pull requests must be reviewed and accepted by a
 Collaborator with sufficient expertise who is able to take full
 responsibility for the change. In the case of pull requests proposed
 by an existing Collaborator, an additional Collaborator is required
-for sign-off. Consensus should be sought if additional Collaborators
-participate and there is disagreement around a particular
-modification. See [Consensus Seeking Process](#consensus-seeking-process) below
-for further detail on the consensus model used for governance.
+for sign-off.
+
+If one or more Collaborators oppose a proposed change, then the change can not
+be accepted unless:
+
+* Discussions and/or additional changes result in no Collaborators objecting to
+  the change. Previously-objecting Collaborators do not necessarily have to
+  sign-off on the change, but they should not be opposed to it.
+* The change is escalated to the CTC and the CTC votes to approve the change.
+  This should be used only after other options (especially discussion among
+  the disagreeing Collaborators) have been exhausted.
 
 Collaborators may opt to elevate significant or controversial modifications to
 the CTC by assigning the `ctc-review` label to a pull request or issue. The