Just to play devil's advocate:
One thing you may want to consider is that your current documentation might be suboptimal - no one may be reading your documentation because it isn't useful (to them).
- How easy is it to find your documentation in the first place?
- How easy is it to find a given topic within your documentation?
- Is there a clear path for a novice user to learn about your program?
- What's the learning curve like? Is there a good progression from complete newbie to experienced user, or do you go straight from trivial examples to a reference manual dump?
- Do you have multiple ways of finding information based on different mental models/outlook? (That is, things like tutorials, FAQs, demos, reference manuals - e.g. not everyone wants to puzzle out the answer to their question from a Backus–Naur grammer, even if it is technically the most accurate way of representing the information.)
- Why aren't people reading your documentation? And no, "because they're ungrateful, lazy schmucks" is not a sufficient answer, at least not if you want to get them to change their behavior.
Looking at you website, it looks like you could highlight "Documentation" more. On the main page, you have 'Download' 'Demo' and 'GitHub' as main buttons, but documentation gets a tiny text-only link. Documentation is at least as important to your users as a GitHub link - why not promote it?
In the upper right you do have a "Getting Started" link, but phrasing could be better. E.g. what will people who are thinking "I don't need to get started - I'm already using it; I just have a question about details" click? You have the "Help" button, but that's a bit confusing - is it "I would like to help this Open Source project"? "Help" in other sites also tends to be more "about this site/contact us" - to be honest, my eyes completely skipped over that link as useless boilerplate the first few times I saw it.
Even when you click on the "Getting Started" link, phrasing the links could be better. For example "navigating the code". I don't want to "navigate" Userfrosting, I want to "use" it. I guessing a fair number of users are skipping that page because they think it's an in-depth nitty-gritty code architecture page, rather than (apparently) your main documentation page.
The tutorials link is good ... but you only have the two. If you are getting repeated questions on the same topic, it's probably worth it to make some tutorials about that topic. This is especially true if you're targeting the novice user. You have to expect that they'll come in with little to none of the knowledge that you take for granted. There has to be an easy (for them) way of getting that knowledge, even if it's not directly related to your software.
Cross linking is also good. The "Components" link on "Getting Started" would be the spot to go to get an overview about the various parts of your program and how to use them, except that it has no links, making it hard to get more information about those parts. (E.g. if I wanted to know how to "Control privileges for users and groups", there's no indication of where I would go to find out.)
In the "Get Help" section on your main page, when I click on "Using Userfrosting", I get an interstitial pop up, and if I blindly click through (which, let's be honest, most people will do) I get dumped back to the front page. That is to say, the one link that - to me - would be the most important documentation link doesn't actually do anything. (Note that this is the same reason that popups on download or steps in the installer won't work - if the popups/steps are hoops to jump through rather than things which provide immediate benefits to the user, people will skip them.)
Finally, you have to think about searchability. Not just "how would I, as an experienced user, search for this information?" but "how would someone who has little to no clue about my software find this information, keeping in mind they might not know what the appropriate keywords are?" First off, your website has no search box available. If I want to search your documentation, I can't do it from your site, instead I have to go to an external search engine and be knowledgeable enough to know about the site restriction syntax, etc.
Even if I do a plain Google search, I'm not much better. For example, I typed "render PHP Userfrosting". Even without the site restrictions on search, I do get related pages, but nothing that a quick glance tells me anything related to rendering PHP (specifically). There might be synthesizable information in there somewhere, but I have ~2,000 Google results for this search, and others from the other search terms I try. Realistically, I'm giving each search result maybe 10 seconds before I give up and go onto the next one. Is there a specific paragraph in the documentation which specifically and directly answers this question? If so, why might I not be finding it?
I want to emphasize that last point. Roughly speaking, if you can't answer "unresearched, quick-fix questions" by a literal cut-and-paste of a single paragraph from the documentation, then either your documentation isn't comprehensive enough or the questions are more complex than you're giving them credit for.
While it's true you will get a fraction of people who will never read your documentation no matter how easy it is to use, the threshold for "giving up" is a range. Each person has a varying level of hassle which they're willing to tolerate. It's not just those who immediately ask others for help and those who extensively scour the documentation to ask comprehensively researched questions. Depending on how hard you make it to use your documentation, you'll get more or fewer people who will make the attempt. Your goal is to lower the hassle level for using the documentation as far as you can.