add change log entry

draft-ietf-httpbis-semantics-latest.xml

@@ -13464,6 +13464,7 @@ transfer-coding = &lt;transfer-coding, see <xref target="Messaging" x:fmt="," x:
 
 <section title="Since draft-ietf-httpbis-semantics-12" anchor="changes.since.12">
 <ul x:when-empty="None yet.">
+  <li>In <xref target="acks"/>, added acks for the work since 2014 (<eref target="https://github.com/httpwg/http-core/issues/442"/>)</li>
   <li>In <xref target="field-extensibility"/>, explain why new fields need to be backwards-compatible (<eref target="https://github.com/httpwg/http-core/issues/448"/>)</li>
   <li>In <xref target="field-order"/>, constrain field combination to be within a section (<eref target="https://github.com/httpwg/http-core/issues/454"/>)</li>
   <li>In <xref target="http.date"/>, mention that caching relaxes date sensitivity (<eref target="https://github.com/httpwg/http-core/issues/473"/>)</li>