Fixing mistakes from math's thesis and put that to the Internet?
Yes, several people have done that (including myself, though the errors were typos). It is almost always looked upon positively in the academic community.

Will the industry look positively upon it? Not sure. On the one hand, it's a positive that you are taking responsibility for what you wrote and correcting the record despite not being required to. On the other hand, it's a negative (for them) that you are still doing research despite intending to leave academia. Most realistically, they won't care or even notice.

Do you have to disclaim that it is your thesis? I don't think so. Writing "corrected version of my thesis" or "thesis (updated)" should be perfectly enough; I don't recall anyone getting in trouble for it. Out of an abundance of caution, I would remove whatever parts of it signal that it is literally the version you submitted -- such as the university's logo and whatever statement you made on the first page about it being your thesis. (Readers won't care about them anyway.)

Don't declare it "learning material", though, unless it has genuine expository value.