docs: update lib mode example (#8279)

Author: sachinraja

docs/config/index.md

@@ -257,8 +257,8 @@ export default defineConfig(({ command, mode }) => {
   {
     "exports": {
       ".": {
-        "import": "./index.esm.mjs",
-        "require": "./index.cjs.js"
+        "import": "./index.mjs",
+        "require": "./index.js"
       }
     }
   }

docs/guide/build.md

@@ -161,7 +161,7 @@ Running `vite build` with this config uses a Rollup preset that is oriented towa
 ```
 $ vite build
 building for production...
-[write] my-lib.es.mjs 0.08kb, brotli: 0.07kb
+[write] my-lib.mjs 0.08kb, brotli: 0.07kb
 [write] my-lib.umd.js 0.30kb, brotli: 0.16kb
 ```
 
@@ -172,10 +172,10 @@ Recommended `package.json` for your lib:
   "name": "my-lib",
   "files": ["dist"],
   "main": "./dist/my-lib.umd.js",
-  "module": "./dist/my-lib.es.mjs",
+  "module": "./dist/my-lib.mjs",
   "exports": {
     ".": {
-      "import": "./dist/my-lib.es.mjs",
+      "import": "./dist/my-lib.mjs",
       "require": "./dist/my-lib.umd.js"
     }
   }