Add better troubleshooting

I am getting a cart undefined error or other GraphQL errors

Author: w3bdesign

README.md

@@ -81,7 +81,7 @@ The current release has been tested and is confirmed working with the following
 
 ## Troubleshooting
 
-**I am getting a cart undefined error?**
+**I am getting a cart undefined error or other GraphQL errors?**
 
 Check that you are using the 0.6.1 version of the WooGraphQL plugin