I personally don't see how open source authors would be incentivized to spend time integrating their Github docs with a commercial, ad-based system like SO Docs.

For closed source subjects that have few resources for examples, like Obj-C, I could see a use.

However, many SO answers rapidly become outdated, especially in the less popular subjects. And the more popular subjects have some really poor questions and answers. Right now SO does a mediocre job of mediating the outdated or misinformed answers that have sat, so I don't see how that will change with SO Docs. In fact since docs are more taken as truth than random internet answers, I imagine it could get much worse.