docs: Add default redirect

docs/book.toml

@@ -5,6 +5,9 @@ language = "en"
 multilingual = false
 src = "src"
 
+[output.html.redirect]
+"/index.html" = "./about.html"
+
 [output.html]
 git-repository-url = "https://git.shivering-isles.com/shivering-isles/infrastructure-gitops/-/tree/main/docs"
 edit-url-template = "https://git.shivering-isles.com/-/ide/project/shivering-isles/infrastructure-gitops/edit/main/-/docs/{path}"