Digital Humanities is a broad interdisciplinary field as well as an ever-evolving one. Therefore, the readings are both broad and hyperspecific. I would recommend sticking to books published in the last 10 years, so they mention projects and tools that are still available online. Older books are useful for tracking how we got to our current moment in DH, but can be frustrating.
On this page, you can find some good general recommendations, and on the sub-pages, you can find books on specific topics or from popular series within the field.
Debates in the Digital Humanities