feat(next-codemod): add upgrade command

packages/next-upgrade/README.md

@@ -0,0 +1,31 @@
+# @next/upgrade
+
+Upgrade Next.js apps to newer or beta versions with one command.
+
+# Build
+
+To build the package locally, go to `packages/next-upgrade` and run:
+
+```bash
+pnpm build && pnpm link --global
+```
+
+In your Next.js app, add the following to your `package.json`:
+
+```json
+"dependencies": {
+  "@next/upgrade": "path/to/local/next.js/packages/next-upgrade"
+}
+```
+
+Finally, run:
+
+```bash
+pnpm i
+```
+
+Now you can use the package!
+
+```bash
+npx @next/upgrade
+```