docs: fix Forgejo webhook and hub URL drift

Remove the Forgejo example that suggests an empty webhook secret.
This setup cannot work because Forgejo/Gitea validation requires a
signature and a non-empty shared secret.

Align the remaining hub-url examples with the Artifact Hub API
default used by the shipped ConfigMap and settings defaults. This
keeps the architecture and OpenShift installation docs consistent
with the main config reference.

Signed-off-by: Chmouel Boudjnah <chmouel@redhat.com>

Author: chmouel

docs/content/docs/dev/architecture.md

@@ -408,8 +408,8 @@ data:
   # Application settings
   application-name: "Pipelines as Code"
 
-  # Tekton Hub URL
-  hub-url: "https://api.hub.tekton.dev/v1"
+  # Artifact Hub API URL
+  hub-url: "https://artifacthub.io/api/v1"
 
   # Remote tasks support
   remote-tasks: "true"

docs/content/docs/installation/openshift.md

@@ -57,7 +57,7 @@ spec:
           enable-cancel-in-progress-on-pull-requests: 'false'
           enable-cancel-in-progress-on-push: 'false'
           skip-push-event-for-pr-commits: 'true'
-          hub-url: 'https://artifacthub.io'
+          hub-url: 'https://artifacthub.io/api/v1'
           hub-catalog-type: 'artifacthub'
           error-detection-max-number-of-lines: '50'
           error-detection-simple-regexp: >-

docs/content/docs/providers/forgejo.md

@@ -93,13 +93,10 @@ kubectl -n target-namespace create secret generic forgejo-webhook-config \
   --from-literal webhook.secret="SECRET_AS_SET_IN_WEBHOOK_CONFIGURATION"
 ```
 
-If you configured an empty webhook secret, use an empty string:
-
-```shell
-kubectl -n target-namespace create secret generic forgejo-webhook-config \
-  --from-literal provider.token="TOKEN_AS_GENERATED_PREVIOUSLY" \
-  --from-literal webhook.secret=""
-```
+{{< callout type="warning" >}}
+Forgejo and Gitea webhook validation requires a non-empty shared secret.
+Do not set `webhook.secret` to an empty string.
+{{< /callout >}}
 
 ### Create the Repository CR