Documentation: fixed install instruction in README.md.

evilebottnawi · evilebottnawi · commit ac503a0e584c · 2016-12-30T12:06:50.000+03:00
diff --git a/README.md b/README.md
@@ -14,7 +14,7 @@ Awesome generator robots.txt.
 ## Installation
 
 ```shell
-npm install generate-robotstxt
+npm install --save-dev generate-robotstxt
 ```
 
 ## Usage
