Add badge for "Check Prettier Formatting" workflow to readme

The badges provide a prominent indication of the repository's CI status at a glance. This may help to bring potential
issues to the attention of the maintainers.

Author: per1234

Diff for: README.md

@@ -6,6 +6,7 @@
 [![Check Markdown status](https://github.com/arduino/arduino-lint/actions/workflows/check-markdown-task.yml/badge.svg)](https://github.com/arduino/arduino-lint/actions/workflows/check-markdown-task.yml)
 [![Docs Status](https://github.com/arduino/arduino-lint/workflows/Publish%20documentation/badge.svg)](https://github.com/arduino/arduino-lint/actions?workflow=Publish+documentation)
 [![Codecov](https://codecov.io/gh/arduino/arduino-lint/branch/main/graph/badge.svg?token=nprqPQMbdh)](https://codecov.io/gh/arduino/arduino-lint)
+[![Check Prettier Formatting status](https://github.com/arduino/arduino-lint/actions/workflows/check-prettier-formatting-task.yml/badge.svg)](https://github.com/arduino/arduino-lint/actions/workflows/check-prettier-formatting-task.yml)
 [![Check General Formatting status](https://github.com/arduino/arduino-lint/actions/workflows/check-general-formatting-task.yml/badge.svg)](https://github.com/arduino/arduino-lint/actions/workflows/check-general-formatting-task.yml)
 [![Check Shell Scripts status](https://github.com/arduino/arduino-lint/actions/workflows/check-shell-task.yml/badge.svg)](https://github.com/arduino/arduino-lint/actions/workflows/check-shell-task.yml)
 [![Check Certificates status](https://github.com/arduino/arduino-lint/actions/workflows/check-certificates.yml/badge.svg)](https://github.com/arduino/arduino-lint/actions/workflows/check-certificates.yml)