[3.12] gh-114332: Fix the flags reference for ``re.compile()`` (GH-114334) (#114339)

[3.12] gh-114332: Fix the flags reference for ``re.compile()`` (GH-114334) (#114339)

gh-114332: Fix the flags reference for ``re.compile()`` (GH-114334)

The GH-93000 change set inadvertently caused a sentence in re.compile()
documentation to refer to details that no longer followed. Correct this
with a link to the Flags sub-subsection.

(cherry picked from commit 567a85e9c15a3f7848330ae7bef3de2f70fc9f97)

Co-authored-by: David H. Gutteridge <dhgutteridge@users.noreply.github.com>
Co-authored-by: Adam Turner <9087854+aa-turner@users.noreply.github.com>