Fix the ROUGE_path in the README

Fix the ROUGE_path in the README

Author: Yogayu

README.md

@@ -72,7 +72,7 @@ After putting system/reference files as above, you can evaluate ROUGE metrics as
 ```
 from pythonrouge.pythonrouge import Pythonrouge
 
-ROUGE = sys.argv[1] #ROUGE-1.5.5.pl
+ROUGE_path = sys.argv[1] #ROUGE-1.5.5.pl
 data_path = sys.argv[2] #data folder in RELEASE-1.5.5
 
 # initialize setting of ROUGE, eval ROUGE-1~4, SU4