We already provide official documentation for the addon SDK, which should be straightforward for someone with existing JavaScript skills to make use of. Teaching beginners how to write JavaScript and training them up to the level that they can use the SDK is out of the scope of our responsibilities so is not something we will consider at this time.
Since I can't edit my comment, I'll just append this: Given the javascript tutorial Ashley has been working on, my comment about "expanding your ideas about what to teach people" is unfair. Those tutorials are very well done, thank you.
I believe what they're asking for isn't a complete course on web programming, but a step by step example of creating a plugin for Construct specifically. That doesn't already exist - the SDK documentation isn't a tutorial and can be a bit unapproachable even for those of us who do have programming experience. Tutorials that involve programming but which don't attempt to explain all the intricacies of programming are quite useful for getting some learners over the initial wall, which is why they are so plentiful for Unreal, Unity, GMS2, etc. They get people rolling in the right direction and help them understand how everything fits together in a more guided way, even if they leave unanswered questions about some of the details. That can be a good thing, because when starting out, a learner can be so overwhelmed that they don't even know what questions to ask - high-level tutorials can help illuminate the most important gaps in knowledge. I know writing plugins for Construct is complicated and fairly difficult (boy, do I know it) and there is quite a bit of knowledge one needs to become proficient at it, but please consider expanding your ideas about what's worth teaching people that are motivated to expand your software but unsure where to start. All that said, I assume you don't have time to spend on such a task yourselves, but perhaps recruiting someone from the community to create a simple plugin tutorial series would be worth the investment.