Remove tokens from badge URLs in documentation

[pboling]

DX has become very important. It used to be the case that I had many badge images in my readmes that each required a unique token in the query string to be passed with the requet for the asset. Most of the CodeCoverage tools, Dependency checking tools, and others required these tokens.

It was incredibly onerous on developers trying to normalize their maintenance work to have to check and recheck these tokens for correctness, and that they weren't accidentally overwritten by layout updates across many repositories.

I use many badges in my repos, and have noticed that all of these tokens are no longer required.

Not even by CodeCov.

Except the documentation in the app implies that they are. They are still provided in the links to copy and add to READMEs. But I just tested without the token, and it works fine.

Example:

Works: https://codecov.io/gh/kettle-rb/kettle-test/graphs/tree.svg?token=4YOMR0SJRI

[![kettle-test coverage graph][🔑codecov-g]][gh]

🔑codecov-g: https://codecov.io/gh/kettle-rb/kettle-test/graphs/tree.svg?token=4YOMR0SJRI
gh: https://github.com/kettle-rb/kettle-test

Also works: https://codecov.io/gh/kettle-rb/kettle-test/graphs/tree.svg

[![kettle-test coverage graph][codecov-g]][gh]

codecov-g: https://codecov.io/gh/kettle-rb/kettle-test/graphs/tree.svg
gh: https://github.com/kettle-rb/kettle-test

Please dump the tokens in the dustbin of history! Tokens like these make maintainer's lives measurably worse.