This extension is not maintained as part of the Entity Framework Core project. When considering a third party extension, be sure to evaluate quality, licensing, support, etc. to ensure they meet your requirements.
LinqKit.Microsoft.EntityFrameworkCore is a free set of extensions for LINQ to SQL and EntityFrameworkCore power users. With Include(...) and IDbAsync support.
The following resource will help you get started with LinqKit.Microsoft.EntityFrameworkCore.