convert : note MiniCPM5-2B shares the MiniCPM5-1B tokenizer

[cyxu0401]

Follow-up to #23384 (MiniCPM5-1B), now that
openbmb/MiniCPM5-2B and
openbmb/MiniCPM5-2B-GGUF
are public.

Comment-only change — no behaviour change.

MiniCPM5-2B ships a byte-identical tokenizer.json to 1B
(md5 ee55db96827d21929c7c5db2092596a8), so running the
convert_hf_to_gguf_update.py recipe against it reproduces the hash that is
already in the table:

36f3066e97b7f3994b379aaacde306c1444c6ae84e81a5ae3cd2b7ed3b8c42d4   (187 tokens on CHK_TXT)

Verified against four copies of the file — HF 1B, HF 2B, and two local
checkpoints — all identical.

So 2B already converts correctly today and needs no code change. This commit
only records why, because the obvious move for the next person adding 2B is
to append a second entry, and that would be a silent regression:

• entries in get_vocab_base_pre() are sequential if statements, not
  elif, so a second entry carrying the same hash placed later wins for
  both models — see the existing mpt/olmo and bert-bge/jina-v2-en
  pairs, where the later entry already shadows the earlier one;
• renaming the pre type away from minicpm5 would break every GGUF already
  published with tokenizer.ggml.pre = "minicpm5", including openbmb's own
  1B and 2B releases.

The note is deliberately kept on one line: get_existing_models() in
convert_hf_to_gguf_update.py matches the if chkhsh == ... / res = ...
pair with a regex that tolerates only a single line between them, so splitting
the comment across two lines breaks regeneration. Confirmed by trying it.

The chat template for 2B is a separate matter and is in its own PR.

[ggml-gh-bot]

Hi @cyxu0401, thanks for your contribution!

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[CISC]

It doesn't work like that, the comment is autogenerated and we will notice if anyone tries to add a duplicate.