Release 26.1 docs (#1643)

Co-authored-by: Joyce Fee <102751339+Feediver1@users.noreply.github.com>
Co-authored-by: Kat Batuigas <36839689+kbatuigas@users.noreply.github.com>
Co-authored-by: Gellért Peresztegi-Nagy <gellert.nagy@redpanda.com>
Co-authored-by: Nicolae Vartolomei <nv@redpanda.com>
Co-authored-by: Kat Batuigas <kbatuigas@gmail.com>
Co-authored-by: Michael Ernest <michael.ernest@contractor.redpanda.com>
Co-authored-by: micheleRP <michele@redpanda.com>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: Paulo Borges <paulohtb6@gmail.com>
Co-authored-by: David Yu <david.yu@redpanda.com>
Co-authored-by: Michael Ernest <michael.ernest@gmail.com>
Co-authored-by: David Yu <yongshinyu@gmail.com>

Author: 10 people

antora.yml

@@ -1,13 +1,13 @@
 name: ROOT
 title: Self-Managed
-version: 25.3
+version: 26.1
 start_page: home:index.adoc
 nav:
 - modules/ROOT/nav.adoc
 asciidoc:
   attributes:
     # Date of release in the format YYYY-MM-DD
-    page-release-date: 2025-11-19
+    page-release-date: 2026-03-31
     # Only used in the main branch (latest version)
     page-header-data:
       order: 2
@@ -17,16 +17,16 @@ asciidoc:
     # Fallback versions
     # We try to fetch the latest versions from GitHub at build time
     # --
-    full-version: 25.3.11
-    latest-redpanda-tag: 'v25.3.11'
+    full-version: 26.1.1
+    latest-redpanda-tag: 'v26.1.1'
     latest-console-tag: 'v3.3.1'
-    latest-release-commit: '6aa5af28b020b66e5caa966094882b7260497a53'
+    latest-release-commit: '35a825c9c1880ebeedf4c18bb8c6cceaa63566c1'
     latest-operator-version: 'v2.3.8-24.3.6'
     operator-beta-tag: ''
     helm-beta-tag: ''
     latest-redpanda-helm-chart-version: ''
-    redpanda-beta-version: '25.3.1-rc4'
-    redpanda-beta-tag: 'v25.3.1-rc4'
+    redpanda-beta-version: ''
+    redpanda-beta-tag: ''
     console-beta-version: ''
     console-beta-tag: ''
     # --