Update README.md

Author: sserrata

README.md

@@ -46,7 +46,7 @@ From PyPI:
 
 ## Obtaining and Using OAuth 2.0 Tokens
 
-If you're an app developer, work with your Developer Relations representative to obtain your OAuth2 credentials. API Explorer may optionally be used to generate a Developer Token, which can also be used to authenticate with the API. For details on API Explorer developer tokens, please visit <https://cortex.pan.dev>.
+If you're an app developer, work with your Developer Relations representative to obtain your OAuth2 credentials. API Explorer may optionally be used to generate a Developer Token, which can also be used to authenticate with the API. For details on API Explorer developer tokens, please visit <https://cortex.pan.dev/docs/learn/developer_tokens>.
 
 # Example