Add pub badge to readme (dart-lang/lints#7)

pkgs/lints/README.md

diff --git a/pkgs/lints/README.md b/pkgs/lints/README.md
index 98fa9f0..796fbd8 100644
--- a/pkgs/lints/README.md
+++ b/pkgs/lints/README.md
@@ -1,3 +1,5 @@
+[![pub package](https://img.shields.io/pub/v/lints.svg)](https://pub.dev/packages/lints)
+
 This repo contains official Dart and Flutter lint rules.
 
 [![Build Status](https://github.com/dart-lang/lints/workflows/validate/badge.svg)](https://github.com/dart-lang/lints/actions)