readme : add Aquila-7B model series to supported models (#2487)

* support bpe tokenizer in convert

Signed-off-by: ldwang <ftgreat@gmail.com>

* support bpe tokenizer in convert

Signed-off-by: ldwang <ftgreat@gmail.com>

* support bpe tokenizer in convert, fix

Signed-off-by: ldwang <ftgreat@gmail.com>

* Add Aquila-7B models in README.md

Signed-off-by: ldwang <ftgreat@gmail.com>

* Up Aquila-7B models in README.md

Signed-off-by: ldwang <ftgreat@gmail.com>

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Signed-off-by: ldwang <ftgreat@gmail.com>
Co-authored-by: ldwang <ftgreat@gmail.com>