docs(#23): update docs for rule folder-naming-convention

Author: dukeluo

docs/rules/folder-naming-convention.md

@@ -6,7 +6,7 @@ Allows you to enforce a consistent naming pattern for the name of the specified
 
 This rule aims to format the name of the specified folder. This rule uses the glob match syntax to match target folders and declare the naming pattern for the folder name.
 
-There are six naming conventions built into this rule, including `CAMEL_CASE`, `PASCAL_CASE`, `SNAKE_CASE`, `KEBAB_CASE`, `SCREAMING_SNAKE_CASE` and `FLAT_CASE`.
+There are six basic naming conventions built into this rule, including `CAMEL_CASE`, `PASCAL_CASE`, `SNAKE_CASE`, `KEBAB_CASE`, `SCREAMING_SNAKE_CASE` and `FLAT_CASE`.
 
 | Formatting | Name |
 |---|---|
@@ -17,6 +17,8 @@ There are six naming conventions built into this rule, including `CAMEL_CASE`, `
 | HELLO_WORLD | `SCREAMING_SNAKE_CASE` |
 | helloworld | `FLAT_CASE` |
 
+And there are a naming convention `NEXT_JS_APP_ROUTER_CASE` for the Next.js app router, which is used to format its folder name.
+
 If the rule had been set as follows:
 ```js
 ...