Fix cloud env var in readme (#4584)

stephentuso · flovilmart · commit f03e35ff76fe · 2018-03-06T19:27:09.000-05:00
diff --git a/README.md b/README.md
@@ -350,7 +350,7 @@ PARSE_SERVER_APPLICATION_ID
 PARSE_SERVER_MASTER_KEY
 PARSE_SERVER_DATABASE_URI
 PARSE_SERVER_URL
-PARSE_SERVER_CLOUD_CODE_MAIN
+PARSE_SERVER_CLOUD
 ```
 
 The default port is 1337, to use a different port set the PORT environment variable:
