Add mention of the "Ethereum Signed Message" prefix to the eth.personal.sign documentation

[montyly]

Hi, thank you for maintaining web3js!
The following is an issue related to the documentation that might mislead users.

Expected behavior

The documentation of eth.personal.sign should detail the hash schema used.

Actual behavior

The current documentation does not indicate that the message to be signed is prefixed with:

"\x19Ethereum Signed Message:\n" + message.length

This might lead to the incorrect usage of the library.

Note that the documentation of eth.accounts.sign does mention the prefix:

Steps to reproduce the behavior

Error Logs

Versions

https://github.com/ethereum/web3.js/tree/7ff00822966aef2bd0588a5b39ff2f3eba6acfd1

[axelgalicia]

Hello @montyly , please let me know if this pull request fulfills the expected outcome of your requirement. I will be happy to update it in case there is a missing part.

Thanks

[montyly]

#2295 fixes the issue, thank you!