refactor readme

README.md

@@ -16,12 +16,13 @@ python-terraform is a python module provide a wrapper of `terraform` command lin
     t = Terraform()
     return_code, stdout, stderr = t.<cmd_name>(*arguments, **options)
 
-**Note**: method name same as reserved keyword like `import` could be called directly
-by adding `_cmd` after command name
+**Note**: method name same as reserved keyword like `import` won't be accepted by python interpreter,
+to be able to call the method, you could call cmd_name by adding `_cmd` after command name, for example,
+`import` here could be called by
 
     from python_terraform import Terraform
     t = Terraform()
-    return_code, stdout, stderr = t.<cmd_name>_cmd(*arguments, **options)
+    return_code, stdout, stderr = t.import_cmd(*arguments, **options)
 
 or just call cmd method directly