Fix developer hub link (#473)

Fix developer hub link

Author: jonnyom

README.md

@@ -28,7 +28,7 @@ Using bundler:
 
 ### Configure your client
 
-> If you already have a personal access token you can find it [here](https://app.intercom.io/a/apps/_/developer_hub/). If you want to create or learn more about personal access tokens then you can find more info [here](https://developers.intercom.io/docs/personal-access-tokens).
+> If you already have a personal access token you can find it [here](https://app.intercom.io/a/apps/_/developer-hub/). If you want to create or learn more about personal access tokens then you can find more info [here](https://developers.intercom.io/docs/personal-access-tokens).
 
 ```ruby
 # With an OAuth or Personal Access token: