[ci-skip] Add Buildkite Badge

Author: ChrisRackauckas

README.md

@@ -3,6 +3,8 @@
 [![Join the chat at https://julialang.zulipchat.com #sciml-bridged](https://img.shields.io/static/v1?label=Zulip&message=chat&color=9558b2&labelColor=389826)](https://julialang.zulipchat.com/#narrow/stream/279055-sciml-bridged)
 [![Global Docs](https://img.shields.io/badge/docs-SciML-blue.svg)](https://docs.sciml.ai/DiffEqDocs/stable/)
 
+[![Build status](https://badge.buildkite.com/21561431a9349125d0146aff52103e0fc26f17b390d974e8aa.svg)](https://buildkite.com/julialang/diffeqdocs-dot-jl)
+
 [![ColPrac: Contributor's Guide on Collaborative Practices for Community Packages](https://img.shields.io/badge/ColPrac-Contributor's%20Guide-blueviolet)](https://github.com/SciML/ColPrac)
 [![SciML Code Style](https://img.shields.io/static/v1?label=code%20style&message=SciML&color=9558b2&labelColor=389826)](https://github.com/SciML/SciMLStyle)