docs: update css-modules to CSS Modules (#422)

Author: 9aoy

website/docs/en/guide/migration/modernjs-module.mdx

@@ -145,9 +145,9 @@ declare module '*.scss' {
 }
 ```
 
-## css-modules
+## CSS Modules
 
-If you use css-modules in your `Modern.js Module`, add the following changes:
+If you use CSS Modules in your `Modern.js Module`, add the following changes:
 
 ```js title="rslib.config.ts"
 import { defineConfig } from '@rslib/core';
@@ -159,7 +159,7 @@ export default defineConfig({
       //...
       output: {
         cssModules: {
-          // the css-modules options are 1:1 the same as in the official "css-modules" package
+          // the CSS Modules options are 1:1 the same as in the official "css-modules" package
           localIdentName: '[local]--[hash:base64:5]',
         },
       },