docs: extra_suffix_delimiters is additive; the comma is not replaceable

Verified live: with ' - ' configured, comma-split suffix groups parse
unchanged. The comma is structural (the same reading that parses
'Family, Given' input), not a configurable suffix delimiter.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: derek73

docs/customize.rst

@@ -90,8 +90,9 @@ listed below.
        Defaults to empty — see the routing example below.
    * - ``extra_suffix_delimiters``
      - ``frozenset[str]``
-     - Adds separators (beyond a comma) that split suffix groups, e.g.
-       ``" - "`` for ``"Jane Smith, RN - CRNA"``.
+     - Adds separators that split suffix groups, e.g. ``" - "`` for
+       ``"Jane Smith, RN - CRNA"``. Additions only — the comma always
+       splits suffix groups and cannot be replaced.
    * - ``lenient_comma_suffixes``
      - ``bool``
      - Allows a segment after a comma to be read as a suffix using

nameparser/_policy.py

@@ -86,7 +86,11 @@ class Policy:
     #: nickname set (maiden wins, see __post_init__), so
     #: maiden_delimiters={("(", ")")} is the whole recipe (#274).
     maiden_delimiters: frozenset[tuple[str, str]] = frozenset()
-    #: Separators beyond a comma that split suffix groups (e.g. " - ").
+    #: Additional separators that split suffix groups (e.g. " - " for
+    #: "Jane Smith, RN - CRNA"). Additive only: the comma always
+    #: splits suffix groups and cannot be replaced -- comma handling
+    #: is structural (the same comma reading that parses
+    #: "Family, Given" input), not a configurable delimiter.
     extra_suffix_delimiters: frozenset[str] = frozenset()
     #: Allows a post-comma segment to read as a suffix via the lenient
     #: initial-shaped test; False requires the strict acronym form.