Fix github "shield"

This was displaying the wrong repository URL.

Hopefully this is the last legacy of `serde-yaml`

README.md

@@ -1,7 +1,7 @@
 Serde YAML
 ==========
 
-[<img alt="github" src="https://img.shields.io/badge/github-acatton/serde--yaml-8da0cb?style=for-the-badge&labelColor=555555&logo=github" height="20">](https://github.com/acatton/serde-yaml-ng)
+[<img alt="github" src="https://img.shields.io/badge/github-acatton/serde--yaml--ng-8da0cb?style=for-the-badge&labelColor=555555&logo=github" height="20">](https://github.com/acatton/serde-yaml-ng)
 [<img alt="crates.io" src="https://img.shields.io/crates/v/serde_yaml_ng.svg?style=for-the-badge&color=fc8d62&logo=rust" height="20">](https://crates.io/crates/serde_yaml_ng)
 [<img alt="docs.rs" src="https://img.shields.io/badge/docs.rs-serde__yaml__ng-66c2a5?style=for-the-badge&labelColor=555555&logo=docs.rs" height="20">](https://docs.rs/serde_yaml_ng)
 [<img alt="build status" src="https://img.shields.io/github/actions/workflow/status/acatton/serde-yaml-ng/ci.yml?branch=master&style=for-the-badge" height="20">](https://github.com/acatton/serde-yaml-ng/actions?query=branch%3Amaster)