fix(webhook): explain why webhook edit needs an authorization choice

Gitea 28 drops a webhook's stored authorization header on every edit
that does not send it again, and never returns it, so tea cannot leave
it unchanged. The error offered --clear-authorization as an equal
alternative, which wiped credentials users still needed. It now says
the header is lost unless sent again, asks for it first, and reserves
--clear-authorization for hooks without one.

Signed-off-by: bircni <bircni@icloud.com>

internal/services/webhooks.go

@@ -145,7 +145,7 @@ func (s Webhooks) Edit(ctx context.Context, id int64, opts WebhookOptions) (Webh
 		return Webhook{}, &CapabilityError{Feature: "webhook secret editing", Reason: "Gitea's edit API does not update the signing secret; recreate the hook to rotate it"}
 	}
 	if opts.Authorization == nil {
-		return Webhook{}, &CapabilityError{Feature: "webhook editing without an authorization choice", Reason: "Gitea replaces authorization and can hide its existing value; supply --authorization-header-file or --clear-authorization"}
+		return Webhook{}, &CapabilityError{Feature: "webhook editing without an authorization choice", Reason: "Gitea drops the stored authorization header on every edit and never returns it, so the caller must send it again or clear it"}
 	}
 	current, err := s.get(ctx, id)
 	if err != nil {