[3.13] gh-119287: clarify doc on BaseExceptionGroup.derive and link to it from contextlib.suppress (GH-119657) (#120105)

gh-119287: clarify doc on BaseExceptionGroup.derive and link to it from contextlib.suppress (GH-119657)
(cherry picked from commit 5c02ea8bae2287a828840f5734966da23dc573dc)

Co-authored-by: Irit Katriel <1055913+iritkatriel@users.noreply.github.com>