docs: Add archival notice (#201)

Author: danielledeleo

source/index.rst

@@ -8,6 +8,11 @@
 Universal web app server
 ########################
 
+.. note::
+
+   NGINX Unit no longer receives new features or
+   enhancements from the project maintainers.
+
 NGINX Unit is a lightweight and versatile application runtime
 that provides the essential components for your web application
 as a single open-source server:

source/theme/layout.html

@@ -96,9 +96,8 @@
 </script>
 <!-- End Tealium Universal Tag -->
 
-<!-- Global banner goes here
-    <div id="rennab"><a href="BANNER LINK">BANNER TEXT</a></div>
--->
+<div id="rennab"><a href="https://github.com/nginx/unit?tab=readme-ov-file#nginx-unit">As of October 2025, NGINX Unit is archived and unmaintained.</a></div>
+
 <div id="main">
 <div id="side">
     <h1>

source/theme/static/style.css

@@ -23,7 +23,6 @@ iframe {
     border: none;
 }
 
-/* Saving for future use
 #rennab {
     padding: .3em 0;
     background: #00974d;
@@ -35,7 +34,7 @@ iframe {
 #rennab a {
     color: white;
 }
-*/
+
 
 #main {
     margin: 0 auto;