I still have yet to be convinced that we actually need this.
If it's a good, well-written question, then you should provide an equally good, well-written answer, no matter how "simple" of a question you think it is. We were all beginners at one time, and we all needed the answers to simple questions. This information might be available elsewhere on the web, but it's scattered and far-too-often inaccurate. Having the right answers all in one place was one of the original goals of Stack Overflow, and such a proposal runs directly counter to it.
If it's a bad, poorly-written question, then it qualifies to be closed as "Not A Real Question", and you should do so with prejudice. The problem is not that it's too simple, the problem is that it's bad. We already have a hammer for that kind of nail.
Not to mention, 5 close reasons is quite well enough. If we don't want to unlock any more than 5 migration paths to limit complexity, then we certainly don't need to add any more close reasons, which are often even more difficult to select between.
Regarding the suggestion of a "General Reference" close reason, the only case in which I think that would make sense is when linking to the official documentation when there is already a sufficient explanation (and hopefully a working sample) provided. But that's quite rare in my experience: even the best of documentation can always be expanded on by a knowledgeable expert. Most people don't learn programming languages by reading the documentation. And there are far too many programming languages and related tools that have downright terrible or non-existent documentation. I don't want to see those questions closed as "General Reference" because they're clearly not.
We're inclined to bias our opinions based on our own experiences (and really, what else could we be expected to do?), and that means we think something is "simple" or "intuitive" or "obvious" if we've already encountered it, solved it, and understand it. But that's precisely the kind of knowledge that we joined this site to share with others! There's too much risk for a selection bias with this close reason. What experienced programmers in an area think is "general reference" is hardly what the average programmer in that area thinks is the same. For example, as a Windows programmer, I'd be tempted to close questions regarding the inability to perform cross-threading operations with UI controls as "general reference". But they're clearly not, considering how often the question gets asked and how few people seem to understand the real issues involved.