docs(generator): clarify array_size comment scope

Agent-Logs-Url: https://github.com/igaw/nvme-cli/sessions/ee08f366-cda9-42a6-9df4-84bc0b3d3013

Co-authored-by: igaw <1050803+igaw@users.noreply.github.com>

Author: Copilot

libnvme/tools/generator/generate-accessors.py

@@ -213,7 +213,7 @@ def __init__(self, name, type_str, gen_getter, gen_setter,
         self.gen_setter = gen_setter  # True → emit setter
         self.is_char_array = is_char_array
         self.is_char_ptr_array = is_char_ptr_array
-        self.array_size = array_size  # only valid when is_char_array is True
+        self.array_size = array_size  # only for fixed-size char arrays (char[N])
 
 
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