Fix README.md typo in view generator script (#337)

Co-authored-by: Adrian Co <adrianpetersonco@gmail.com>

Author: akosipc

README.md

@@ -189,7 +189,7 @@ insert  app/assets/stylesheet/application.css
 In order to get a control on datagrid built-in views run:
 
 ``` sh
-rails g datagrid::views
+rails g datagrid:views
 ```
 
 #### Advanced frontend