gh-83156: Add dedicated anchor for regexp syntax elements (#17470)

Co-authored-by: Muse Code (Meta Muse Spark)
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
Co-authored-by: Lukasz Langa <ambv@meta.com>
Co-authored-by: Łukasz Langa <lukasz@langa.pl>

Author: 5 people