Remove the extremely unstable wording from the spec because it's

quite stable so far.

index.html

@@ -109,10 +109,7 @@
     </section>
     <section id='sotd'>
       <p>
-        Implementors need to be aware that this specification is extremely
-        unstable. <strong>Implementors who are not taking part in the
-        discussions will find the specification changing out from under them in
-        incompatible ways.</strong> Vendors interested in implementing this
+        Vendors interested in implementing this
         specification before it eventually reaches the Candidate Recommendation
         phase should <a href="https://github.com/w3c/device-posture">subscribe
         to the repository on GitHub</a> and take part in the discussions.