[3.12] gh-118100: Improve links in `ast.rst` (GH-118101) (#118110)

gh-118100: Improve links in `ast.rst` (GH-118101)
(cherry picked from commit 2aa11cca115add03f39cb6cd7299135ecf4d4d82)

Co-authored-by: Nikita Sobolev <mail@sobolevn.me>
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>