docs(chain.ts): add example of method

Author: TomokiMiyauci

chain.ts

@@ -53,8 +53,15 @@ export class Chain implements Chainable, Responsive {
     this.#handlers = init ?? [];
   }
 
-  /**  Register chainable HTTP handlers.
+  /** Register chainable HTTP handlers.
    * @param handlers HTTP chainable handlers.
+   *
+   * @example
+   * ```ts
+   * import { Chain } from "https://deno.land/x/chain_handler@$VERSION/mod.ts";
+   *
+   * const chain = new Chain().next((request, next) => next(), () => new Response("hello"))
+   * ```
    */
   readonly next = (...handlers: readonly ChainableHandler[]): this => {
     this.#handlers = this.#handlers.concat(handlers);
@@ -63,6 +70,7 @@ export class Chain implements Chainable, Responsive {
   };
 
   /** All registered handlers.
+   *
    * @example
    * ```ts
    * import { Chain } from "https://deno.land/x/chain_handler@$VERSION/mod.ts";
@@ -78,6 +86,16 @@ export class Chain implements Chainable, Responsive {
   /**
    * @param request `Request` object. The `Request` is cloned and not mutate.
    * @param defaultResponse The default `Response` object. Change the response when the {@link handlers} is empty.
+   *
+   * @example
+   * ```ts
+   * import { Chain } from "https://deno.land/x/chain_handler@$VERSION/mod.ts";
+   * import { assertEquals } from "https://deno.land/std/testing/asserts.ts";
+   *
+   * const chain = new Chain()
+   * const response = await chain.respond(new Request("http://localhost"))
+   * assertEquals(response.status, 404)
+   * ```
    */
   readonly respond = (
     request: Request,