docs: add "official"

kenjis · kenjis · commit 811505450863 · 2023-09-19T09:11:56.000+09:00
diff --git a/docs/index.md b/docs/index.md
@@ -2,7 +2,7 @@
 
 ## What is Shield?
 
-Shield is an authentication and authorization framework for CodeIgniter 4. While
+Shield is the official authentication and authorization framework for CodeIgniter 4. While
 it does provide a base set of tools that are commonly used in websites, it is
 designed to be flexible and easily customizable.
 
