Update npm install docs (#464)

EatonZ · web-flow · commit e71751a4228f · 2021-07-13T15:34:40.000-04:00
diff --git a/README.md b/README.md
@@ -41,7 +41,7 @@ please look at
 ## Installation
 
 ```console
-$ npm install postcss-import
+$ npm install -D postcss-import
 ```
 
 ## Usage
