README.md: restore Slack badge (#29984)

diff --git a/README.md b/README.md
index 4f62761d753de4dfff695a5edb3f18839bdefbe5..dbc2295136a82f86e2523053c03c64ad905d3eeb 100644 (file)
--- a/README.md
+++ b/README.md
@@ -53,6 +53,7 @@ Read the [Getting started page](https://getbootstrap.com/docs/4.3/getting-starte
 
 ## Status
 
+[![Slack](https://bootstrap-slack.herokuapp.com/badge.svg)](https://bootstrap-slack.herokuapp.com/)
 [![Build Status](https://github.com/twbs/bootstrap/workflows/Tests/badge.svg)](https://github.com/twbs/bootstrap/actions?workflow=Tests)
 [![npm version](https://img.shields.io/npm/v/bootstrap.svg)](https://www.npmjs.com/package/bootstrap)
 [![Gem version](https://img.shields.io/gem/v/bootstrap.svg)](https://rubygems.org/gems/bootstrap)