Added Xerom to list of Additional Chains using BlockScout.

[fallengravity]

Motivation

Xerom uses blockscout as a backup explorer, figured it would be good to show our support.

Changelog

• Ran a beautifier over the README.md as well as CHANGELOG.md files
• Added Xerom to list of Additional Chains using BlockScout and linked their public instance.

Enhancements

• Ran a beautifier over the README.md as well as CHANGELOG.md files

Bug Fixes

None.

Incompatible Changes

None.

Upgrading

No need.

Checklist for your PR

• I added an entry to CHANGELOG.md with this PR
• If I added new functionality, I added tests covering it.
• If I fixed a bug, I added a regression test to prevent the bug from silently reappearing again.
• I checked whether I should update the docs and did so if necessary
• If I added/changed/removed ENV var, I should update the list of env vars in https://github.com/poanetwork/blockscout/blob/master/docs/env-variables.md to reflect changes in the table here https://poanetwork.github.io/blockscout/#/env-variables?id=blockscout-env-variables. I've set master in the Version column.
• If I add new indices into DB, I checked, that they don't redundant with PGHero or other tools

[vbaranov]

@fallengravity it is awesome to see a new instance of Blockscout 👍

Could you please clean out your PR a little bit? I see too many unnecessary changes https://github.com/poanetwork/blockscout/pull/2646/files.

[fallengravity]

@vbaranov Done :)