Example Dockerfile does not copy .npmc / .yarnrc files

### Verify canary release - [X] I verified that the issue exists in the latest Next.js canary release ### Provide environment information ```bash Operating System: Platform: win32 Arch: x64 Version: Windows 11 Pro Available memory (MB): 32566 Available CPU cores: 16 Binaries: Node: 20.12.2 npm: N/A Yarn: N/A pnpm: 9.10.0 Relevant Packages: next: 14.2.10 // An outdated version detected (latest is 15.0.1), upgrade is highly recommended! eslint-config-next: N/A react: 18.3.1 react-dom: 18.3.1 typescript: 5.5.4 Next.js Config: output: standalone ``` ### Which example does this report relate to? with-docker ### What browser are you using? (if relevant) _No response_ ### How are you deploying your application? (if relevant) _No response_ ### Describe the Bug Currently example `Dockerfile` does not try to copy `.npmrc` / `.yarnrc` files which can lead to issues when installing packages ### Expected Behavior Example `Dockerfile` should attempt to copy those configuration files just like it attempts to copy the lock files ### To Reproduce 1. Add a package from a private registry to your NextJS project 2. Copy the example `Dockerfile` into your project 3. Attempt to build the docker image