chore: clarify that concentric streets are no longer used (#530)

Author: srabraham

web/template/adminroot.templ

@@ -47,8 +47,8 @@ templ AdminRoot(deployment, versionName, versionRef string) {
     </li>
     <li>
       <a href="/ims/app/admin/streets">
-        Event Concentric Streets
-      </a>
+        <s>Event Concentric Streets</s>
+      </a> - no longer used as of late 2025
     </li>
     <li>
       <a href="/ims/app/admin/destinations">

web/template/adminroot_templ.go

@@ -29,8 +29,7 @@ templ AdminStreets(deployment, versionName, versionRef string) {
 @LoadingOverlay()
 @ErrorInfo()
   <p>
-    <strong>IMPORTANT</strong>: this page/the API does not permit editing or removing streets once they've been added. Further edits must be
-    done via SQL against the IMS database. Get it right the first time!
+    <strong>IMPORTANT: as of late 2025, these concentric streets are no longer used by IMS, since addresses are now only free-form strings.</strong>
   </p>
   <p>Each new street must be added with an identifying integer. That ID dictates the order that streets are shown on the Incident page.</p>
   <div class="row" id="event_streets_container">