I really hate the "just google it" responses to questions online. Not only are they rude, they also actively damage the internet as a growing document. Even if you DO want to be an arrogant prick and say "you are a moron and google has the answer", you can do that AND post the answer. Whatever you post online is not a discussion in the moment but rather instantly becomes a part of the internet that will age with it.

Comments will sit forever unchanged, but google results will change. Oftentimes the thread being written in that very moment will become the top google result down the line.

The correct response to a question to which you know the answer, no matter how stupid it is, is:

Optional remark about how the OP should have googled

Single sentence stating the correct answer

A few sentences providing more detail, if more detail is needed

Link to the source, optional but recommended especially if the link has even more detail to read about and especially if you included the "you could have googled this" remark.

(this applies to matters of fact; opinions you usually don't need to cite etc)

If the link isn't to a self-archiving site like wikipedia, and you want to be really thorough, go to https://web.archive.org/ and plug the link into the "save page now" module on the bottom right -- that way if the page goes down or changes in the future, someone who finds the thread in the future can go to the wayback machine and see your link as it was when you made the post

In a similar way, proper etiquette if you post a question and it gets answered in the thread, especially if it gets answered in pieces in multiple replies, OR if you find the solution outside the thread (especially in this case), is to edit your post with a summary of what you found.