Next.js 6.1

This post details the release of Next.js 6.1, focusing on improved hot reloading reliability by removing react-hot-loader and handling hot reloading internally. It introduces the `pageExtensions` configuration for custom page file types (like TypeScript and MDX) and automatically applies `hot-self-accept-loader`. Codebase improvements include moving the `server/build` directory to the top level `build` and renaming `.next/dist` to `.next/server`. It also introduces `next-codemod` to automate the migration from the deprecated `url` property to `withRouter`. Future plans include Webpack 4 for faster builds and optimizations for serverless Next.js to reduce cold start times.