I saw that these chapters are still to be done. I would like to offer to write all or some of them:
Migrating HTTP Modules to Middleware
http://docs.asp.net/en/latest/migration/http-modules.html
Create a New NuGet Package with DNX
https://docs.asp.net/en/latest/dnx/create-package.html
Migrating an Existing NuGet Package Project
https://docs.asp.net/en/latest/dnx/migrate-package.html
My experience in these areas comes from converting my open source NuGet package JSNLog (jsnlog.com; 30,000 downloads) to ASP.NET 5, supporting DNX451 and DNXCORE50.
JSNLog is a JavaScript logging package that lets you log client side exceptions and other events automatically in your server side logs. The jsnlog.js client side library sends all log data to the JSNLog server side component, which hands the data to the user's server side logging package, such as NLog or Serilog.
This started life as an ASP.NET 4.x HTTP Handler. After I converted it, the one JSNLog package can now be used as an ASP.NET 4.x HTTP Handler and OWIN Middleware, and as an ASP.NET 5 Middleware with DNX451 and DNXCORE50.
Please let me know if you want me to write those chapters.
Matt Perdeck