docs: add documentation

Author: chenjiahan

README.md

@@ -2,6 +2,8 @@
 
 An Rsbuild plugin to import TOML files and convert them to JavaScript objects.
 
+> [TOML](https://toml.io/) is a semantically explicit, easy-to-read configuration file format.
+
 <p>
   <a href="https://npmjs.com/package/@rsbuild/plugin-toml">
    <img src="https://img.shields.io/npm/v/@rsbuild/plugin-toml?style=flat-square&colorA=564341&colorB=EDED91" alt="npm version" />
@@ -28,6 +30,37 @@ export default {
 };
 ```
 
+## Example
+
+Suppose the project has the following code in `example.toml`:
+
+```toml title="example.toml"
+hello = "world"
+
+[foo]
+bar = "baz"
+```
+
+After using the TOML plugin, you can reference it as follows:
+
+```js
+import example from "./example.toml";
+
+console.log(example.hello); // 'world';
+console.log(example.foo); // { bar: 'baz' };
+```
+
+## Type Declaration
+
+When you import TOML files in TypeScript code, please create a `src/env.d.ts` file in your project and add the type declarations.
+
+```ts title="src/env.d.ts"
+declare module "*.toml" {
+  const content: Record<string, any>;
+  export default content;
+}
+```
+
 ## License
 
 [MIT](./LICENSE).