A legislative history is a compilation of documents relating to a piece of legislation. These documents are compiled to discover the intent of the legislature in passing the law.
The legislative process in Delaware is similar to the federal legislative process. There's a helpful chart illustrating the Delaware legislative process on the General Assembly's website.
Much of the legislation passed in the Delaware General Assembly is discussed in caucus, with little debate. For this reason, there are few legislative documents published and legislative intent can be difficult to find. The party caucus websites do have some information on recent legislation, mostly just press releases discussing their positions on bills and issues.