feat: add offline plugin & update year

mkdocs.yml

@@ -20,7 +20,7 @@ theme:
   favicon: img/favicon.ico
   custom_dir: custom_theme/
 
-copyright: Copyleft 🄯 2022 Co-op Cloud
+copyright: Copyleft 2023 Co-op Cloud
 
 markdown_extensions:
   - meta
@@ -97,8 +97,9 @@ nav:
     - glossary/index.md
 
 plugins:
-  - search
   - awesome-pages
+  - offline
+  - search
 
 repo_name: coop-cloud/docs.coopcloud.tech
 repo_url: https://git.coopcloud.tech/coop-cloud/docs.coopcloud.tech/