Bug#992296: Acknowledgement (texlive-latex-recommended: index package warns that \markboth and \markright have changed)

[Norman Ramsey]

I have learned that this issue was fixed upstream, but not until
TeXLive 2021.  The fix can be found at

https://github.com/latex3/latex2e/pull/518/commits/ab0cb06c45dd7beca0569a1b4004e5a1d5de0a70