Add issue marker noting Vocabulary URLs might change.

Author: msporny

index.html

@@ -5119,6 +5119,14 @@ <h3>Base Context</h3>
       <section class="normative">
         <h3>Vocabularies</h3>
 
+        <p class="issue" title="(AT RISK) URL values might change during Candidate Recommendation">
+This section lists URL values that might change during the Candidate
+Recommendation phase based on migration of documents to the W3C Technical
+Reports namespace and implementer feedback that requires the referenced URLs to
+be modified. Specifically, it is expected that the github.io links listed
+below will eventually point to W3C TR space.
+        </p>
+
         <p>
 Implementations MUST ensure that the following vocabulary URLs used in the base
 context ultimately resolve to the following files, which are normative: