add copyright for codeigniter

Author: datamweb

mkdocs.yml

@@ -21,6 +21,7 @@ theme:
 
 extra:
   homepage: https://codeigniter.com
+  generator: false
 
   social:
     - icon: fontawesome/brands/github
@@ -29,6 +30,7 @@ extra:
 
 repo_url: https://github.com/codeigniter4/shield
 edit_uri: edit/develop/docs/
+copyright: Copyright © 2023 CodeIgniter Foundation.
 
 markdown_extensions:
   - pymdownx.superfences