Missing tested up to on readme text validator

Start by reading the developer docs here: https://developer.wordpress.org/plugins/wordpress-org/how-your-readme-txt-works/#how-the-readme-is-parsed .

The example readme on that page explains all of what is required, what to put there, and the other optional items.

There are also several readme generators that might help you. One is here: https://tools.wedevs.com/readme/ . Others are available.