Fix double slash for agent url

Author: Starefossen

docs/observability/frontend/README.md

@@ -63,10 +63,10 @@ See below for auto-configuration instructions for when your app is a NAIS applic
 | `https://telemetry.nav.no/collect`             | `prod`      |
 | `https://telemetry.ekstern.dev.nav.no/collect` | `dev`       |
 {% else %}
-| Collector endpoint                                  | Environment |
-| --------------------------------------------------- | ----------- |
-| `<<tenant_url("telemetry.external.prod")>>/collect` | `prod`      |
-| `<<tenant_url("telemetry.external.dev")>>/collect`  | `dev`       |
+| Collector endpoint                                     | Environment |
+| ------------------------------------------------------ | ----------- |
+| `<<tenant_url("telemetry.external.prod", "collect")>>` | `prod`      |
+| `<<tenant_url("telemetry.external.dev", "collect")>>`  | `dev`       |
 {% endif %}
 
 On-premises clusters are not supported.