Fix Incoming Webhooks app page link in doc

The previous link to the Incoming Webhooks app page for Cisco's 
Webex product would never finish loading for me.  This updated link 
seems to load correctly every time.  

Without this link users will need to manually search the Webex 
documentation for notes on how to setup a new incoming link.  

doc/user/project/integrations/webex_teams.md

@@ -13,7 +13,7 @@ You can configure GitLab to send notifications to a Webex Teams space:
 
 ## Create a webhook for the space
 
-1. Go to the [Incoming Webhooks app page](https://apphub.webex.com/applications/incoming-webhooks-cisco-systems-38054).
+1. Go to the [Incoming Webhooks app page](https://apphub.webex.com/applications/incoming-webhooks-cisco-systems-38054-23307).
 1. Select **Connect** and log in to Webex Teams, if required.
 1. Enter a name for the webhook and select the space to receive the notifications.
 1. Select **ADD**.