Fix Readme CI Build status tag (#149)

Co-authored-by: Thomas Judd-Cooper <[email protected]>

Author: KaiSpencer

README.md

@@ -11,7 +11,7 @@
 
 NHS.UK Frontend ported to React
 
-[![GitHub Actions CI Status](https://github.com/NHSDigital/nhsuk-react-components/workflows/CI/badge.svg)](https://github.com/NHSDigital/nhsuk-react-components/actions?query=workflow%3A%22CI+Build%22+branch%3Amain) [![Bundle Size](https://img.shields.io/bundlephobia/minzip/nhsuk-react-components.svg)](https://bundlephobia.com/result?p=nhsuk-react-components)
+[![GitHub Actions CI Status](https://github.com/NHSDigital/nhsuk-react-components/actions/workflows/ci.yml/badge.svg?branch=main)](https://github.com/NHSDigital/nhsuk-react-components/actions?query=workflow%3A%22CI+Build%22+branch%3Amain) [![Bundle Size](https://img.shields.io/bundlephobia/minzip/nhsuk-react-components.svg)](https://bundlephobia.com/result?p=nhsuk-react-components)
 
 ## Coming from 0.x?