Add docs note for Geth v1.9.12 eth_call change

[ryanio]

Description

It was identified in #3456 that geth released a breaking change regarding the default value of from in eth_call.

This means that if you're calling view methods that refer to a msg.sender without explicitly setting a from address in your request options, you may see unexpected behavior.

This PR adds some notes to the changelog and documentation about this change.

After some discourse we decided that we should not brush this change under the rug by modifying the behavior of web3.js, but instead stay consistent with the best practices and recommendations from the node clients.

In web3.js, the from address can be specified on a per-call basis or by setting the defaultAccount property.

Closes #3456

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• I have selected the correct base branch.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• Any dependent changes have been merged and published in downstream modules.
• I ran npm run dtslint with success and extended the tests and types if necessary.
• I ran npm run test:unit with success.
• I have executed npm run test:cov and my test cases do cover all lines and branches of the added code.
• I ran npm run build-all and tested the resulting file/'s from dist folder in a browser.
• I have updated the CHANGELOG.md file in the root folder.
• I have tested my code on the live network.

[coveralls]

Coverage remained the same at 88.596% when pulling f41ccee on gethEthCallChange into 3684fc3 on 1.x.