From what Kotaku has been able to piece together, the documents are confirmed to be real and from the descriptions as well as other details, there is little doubt that while the name Fallout 4 does not appear in these documents, the project is Fallout 4.
While there have been a number of vague rumors and a lot of talk, Bethesda has done a good job at denying the existence of a Fallout 4 project that was on the way. While the rumors have continued, Bethesda has not announced anything officially. We now suspect that an announcement it coming, but it likely will not happen till E3 next year.
Read more here at Kotaku.