Very minor removal of extraneous character in README.md

[andygeorge]

This removes the extraneous backtick character at the end of the readme.

It appears to have been recently added accidentally in #1604.

[github-actions[bot]]

:tada: This PR is included in version 4.1.0 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: