The article discussed as much as an investigation can disclose while it is ongoing. Obviously the FBI found documents however, there is no concrete conclusion about the nature of those documents and the legality of their possession as of yet.
When asking for a source, the best I could find about the Washington Post clarifying what was found was in this most recent article and, to be clear, the article makes absolutely no assertion that the FBI found nothing. Again, in contradiction of the OPs assertion.
What is interesting is that the article now asserts that Trump's intention in keeping the documents is more likely about ego and sentimentality which, given Trump's bombastic and hyperbolic rhetoric on nearly everything, shouldn't be surprising. The Post had previously written an article saying that the documents contain compromising information about intelligence gathering and other highly sensitive material. Where intention doesn't preclude guilt or wrongdoing, the theme amongst the MSM was that Trump was somehow acting in a traitorous and intentional manner. Thus assuming malevolent intentionality.
Now, the Post is saying that there doesn't appear to be any malevolence or intentionally traitorous behavior rather, he was behaving more like a petulant child which, given earlier narratives and evidence, is par for the course.
Ultimately, this raid appears to be more about demonization rather than attempting to actually prevent the leaking of classified documents for profit.
I can appreciate the OPs meme. Further, in the last few days there have been many conservative/right leaning publications asserting basically what the OP posted. Did the FBI find nothing? Clearly they found documents. What was the nature of the documents specifically? Obviously an ongoing investigation can't disclose that. Did Trump keep the documents in order to perpetrate some sort of treasonous activity? The Washington Post seems to think it was done because Trump is petty. Is anyone surprised? Not this fashionista.