So, here's the challenge: if you're going to develop systems software (which is to say, software that is consumed by a fellow software engineer), you're going to find that you're much more likely to hear about how the software doesn't work than how it does. This is frustrating because you -- like every other human -- react much better to praise than to scorn. But here's the leap you need to make: when you have someone taking the time to criticize you in depth, it's because THEY WANT YOU TO SUCCEED. (If they didn't want you to succeed, they wouldn't bother reporting their experiences to you, because they wouldn't actually want you to fix them!)
So as hard as they can be to read sometimes, experiences like the one you replied to are actually essential to you and your project: it is someone who wants you to succeed explaining in detail how you fall short. The proper reply is to thank them for the time they took, apologize for any inconvenience -- and then try to figure out forward progress on the problem that they've identified (which in this case seems as simple as pointing Delvarworld to the nascent "Getting Started" guide). No, this isn't always easy (and you can take solace in the fact that it's hard for the rest of us too) -- but it's essential if you want to develop systems software.
I object to one thing you said. Criticism is often NOT because the critic wants you to succeed. If more than a few people know about your tool, some of them will hate your project and want it to be rejected and die. And they won't necessarily play fair. There are so many ways and so many reasons why an open source tool will be attacked, many of which are not constructive at all, not even honest, just intended to make your project look terrible in public so that they can "win" somehow. This is a social reality of writing tools for other people to use for free.
When I fail to learn a new technology, I prefer to say the technology sucks than to say I'm too stupid to learn it. In this case, I do not really want them to success...
So as hard as they can be to read sometimes, experiences like the one you replied to are actually essential to you and your project: it is someone who wants you to succeed explaining in detail how you fall short. The proper reply is to thank them for the time they took, apologize for any inconvenience -- and then try to figure out forward progress on the problem that they've identified (which in this case seems as simple as pointing Delvarworld to the nascent "Getting Started" guide). No, this isn't always easy (and you can take solace in the fact that it's hard for the rest of us too) -- but it's essential if you want to develop systems software.