update d_kv'annotation in mt5'configuration

[callanwu]

What does this PR do?

Fixes # (issue)

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Who can review?

@stevhliu and @MKhalusova

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[MKhalusova]

Thank you for your contribution! Please make sure that the quality checks pass - here's the contributing guide. It looks like you need to run make style.

[callanwu]

Thank you for your contribution! Please make sure that the quality checks pass - here's the contributing guide. It looks like you need to run make style.

@MKhalusova Hi, thx for your reminder. I have passed all checks!

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint.

[callanwu]

Add reference:
https://huggingface.co/google/mt5-small/blob/main/config.json
modules output of a loaded mt5-small

T5Block(
    (layer): ModuleList(
        (0): T5LayerSelfAttention(
        (SelfAttention): T5Attention(
            (q): Linear(in_features=512, out_features=384, bias=False)
            (k): Linear(in_features=512, out_features=384, bias=False)
            (v): Linear(in_features=512, out_features=384, bias=False)
            (o): Linear(in_features=384, out_features=512, bias=False)
        )
        (layer_norm): T5LayerNorm()
        (dropout): Dropout(p=0.1, inplace=False)
        )
        (1): T5LayerFF(
        (DenseReluDense): T5DenseGatedGeluDense(
            (wi_0): Linear(in_features=512, out_features=1024, bias=False)
            (wi_1): Linear(in_features=512, out_features=1024, bias=False)
            (wo): Linear(in_features=1024, out_features=512, bias=False)
            (dropout): Dropout(p=0.1, inplace=False)
        )
        (layer_norm): T5LayerNorm()
        (dropout): Dropout(p=0.1, inplace=False)
        )
    )
)

[callanwu]

@MKhalusova @patrickvonplaten Can it be merged now? Are there any further improvements needed:)

[ArthurZucker]

Thanks @callanwu 🤗