Fix wif description in setup.md

[azuchi]

Currently, extended WIF is defined, but what we are using is normal WIF.

[Yamaguchi]

こちらも併せてand extend WIF format -> a WIF format に変更していただけると

https://github.com/chaintope/tapyrus-signer/blob/8d1d0e8e9d4a9ff503a8a5f8e57a0b91f4c389f1/src/cli/setup/create_node_vss.rs#L96

https://github.com/chaintope/tapyrus-signer/blob/08729864e9beec8aaee99c8daab574dddb175ba5/src/cli/setup/aggregate.rs#L98

https://github.com/chaintope/tapyrus-signer/blob/8d1d0e8e9d4a9ff503a8a5f8e57a0b91f4c389f1/src/cli/setup/create_block_vss.rs#L107

https://github.com/chaintope/tapyrus-signer/blob/8d1d0e8e9d4a9ff503a8a5f8e57a0b91f4c389f1/src/cli/setup/sign.rs#L125

https://github.com/chaintope/tapyrus-signer/blob/8d1d0e8e9d4a9ff503a8a5f8e57a0b91f4c389f1/src/cli/setup/compute_sig.rs#L184

[azuchi]

@Yamaguchi 修正しました。