Add statement about CR exit criteria.

index.html

@@ -254,6 +254,17 @@
     </section>
 
     <section id='sotd'>
+
+      <p>
+The Working Group is actively seeking implementation feedback for this
+specification. In order to exit the Candidate Recommendation phase, the
+Working Group has set the requirement of at least two independent
+implementations for each mandatory feature in the specification. For details
+on the conformance testing process, see the test suites listed in the
+<a href="https://w3c.github.io/vc-data-integrity/implementations/">
+implementation report</a>.
+      </p>
+
     </section>
 
     <section class="informative">