I don't think it's an apparent contradiction. The first quote is a meta description of the whole article. People would need to know what it's about to read it.
In actual technical documentation, on the other hand, people already know "this is the documentation of program X". And in the various chapters, you can just go ahead and give them a good title, and then go say what it is to say - without first announcing what you'll say.
In actual technical documentation, on the other hand, people already know "this is the documentation of program X". And in the various chapters, you can just go ahead and give them a good title, and then go say what it is to say - without first announcing what you'll say.