add instruction to call `pub get` (dart-lang/lints#21)

diff --git a/pkgs/lints/README.md b/pkgs/lints/README.md
index 15cd96c..45b9139 100644
--- a/pkgs/lints/README.md
+++ b/pkgs/lints/README.md
@@ -39,11 +39,10 @@
 
 For existing apps or packages, take these steps to enable these lints:
 
-1. Add a *dev* dependency on this package to your `pubspec.yaml` file:
+1. In a terminal, located at the root of your package, run this command:
 
-```yaml
-dev_dependencies:
-  lints: ^1.0.0
+```terminal
+dart pub add --dev lints
 ```
 
 2. Create a new `analysis_options.yaml` file, next to the pubspec, that includes