fix example

danreeves · danreeves · commit 8c47eb3c37a1 · 2017-11-14T21:20:46.000Z
diff --git a/README.md b/README.md
@@ -36,7 +36,7 @@ $ npm install --global backstop-crawl
 
   Examples
     $ backstop-crawl http://localhost
-    $ backstop-crawl http://localhost --referenceUrl='https://mycoolsite.com'
+    $ backstop-crawl http://localhost --reference-url='https://mycoolsite.com'
 
 ```
 
