fixup: style, README badge

.buildkite/pipeline.yml

@@ -12,7 +12,8 @@ steps:
     plugins:
       - scionproto/metahook#v0.3.0:
           post-artifact: |
-            cat << EOF | buildkite-agent annotate
+            cat << EOF | buildkite-agent annotate --style "info"
+            ### Build output
             - <a href="artifact://bazel-bin/scion.tar">SCION binaries</a>
             - <a href="artifact://bazel-bin/scion-ci.tar">SCION test tools and utilities binaries</a>
             EOF

README.md

@@ -3,7 +3,7 @@
 [![Slack chat](https://img.shields.io/badge/chat%20on-slack-blue?logo=slack)](https://scionproto.slack.com)
 [![ReadTheDocs](https://img.shields.io/badge/doc-reference-blue?version=latest&style=flat&label=docs&logo=read-the-docs&logoColor=white)](https://docs.scion.org/en/latest)
 [![Documentation](https://img.shields.io/badge/go.dev-reference-007d9c?logo=go&logoColor=white)](https://pkg.go.dev/github.com/scionproto/scion)
-[![Build Status](https://badge.buildkite.com/e7ca347d947c23883ad7c3a4d091c2df5ae7feb52b238d29a1.svg?branch=master)](https://buildkite.com/scionproto/scion)
+[![Nightly Build](https://badge.buildkite.com/b70b65b38a75eb8724f41a6f1203c9327cfb767f07a0c1934e.svg)](https://buildkite.com/scionproto/scion-nightly/builds/latest)
 [![Go Report Card](https://goreportcard.com/badge/github.com/scionproto/scion)](https://goreportcard.com/report/github.com/scionproto/scion)
 [![GitHub issues](https://img.shields.io/github/issues/scionproto/scion/help%20wanted.svg?label=help%20wanted&color=purple)](https://github.com/scionproto/scion/issues?q=is%3Aopen+is%3Aissue+label%3A%22help+wanted%22)
 [![GitHub issues](https://img.shields.io/github/issues/scionproto/scion/good%20first%20issue.svg?label=good%20first%20issue&color=purple)](https://github.com/scionproto/scion/issues?q=is%3Aopen+is%3Aissue+label%3A%22good+first+issue%22)