I know it feels harmless, but this kind of low-effort drive-by PR is loathed by maintainers. It's not contributing anything significant to the project, but requires some of their time and gives you visibility in the changelog.
Personally, I have sent these kinds of PRs out and received only approvals and thanks from maintainers. When in an approver/maintainer role myself, these kinds of PRs are trivial to approve and I appreciate them. The PRs that change a bunch of stuff, are large, hard to review, poorly described, poorly justified, poorly tested, etc., are the annoying ones.
I agree that spelling mistakes in a readme / website / docs should be fixed. Comments, on the other hand, are irrelevant, and not worth pinging the maintainers for unless they are affecting comprehension (not the case here). On a project with 0 PRs open it may be ok, but in more active projects that have dozens/hundreds of PRs at any given time, it's just adding noise.
It's also been a trend in the past few years for people to make this kind of PR, which is very low hanging fruit, just to increase the number of projects they "contributed to" and their profile activity. The author may have not had this intention, but it sure plays into the stereotype.
