add build status

Author: Bitl

README.md

@@ -1,4 +1,6 @@
 # Source SDK 2013 BDS Base
+Build status:
+[![Windows Test Build](https://github.com/BitlDevelopmentStudios/source-sdk-2013-bds-base/actions/workflows/build-windows.yml/badge.svg)](https://github.com/BitlDevelopmentStudios/source-sdk-2013-bds-base/actions/workflows/build-windows.yml)
 
 This is a Source SDK 2013 fork made for the purpose of giving a reliable mod base for currently updated and future Bitl Development Studio (BDS) mod projects.
 This was based off the TF2/64-bit SDK release, and will be updated as the SDK updates.