Add multiple ingresses usage section

Signed-off-by: Fernanda Martins <flmmartins@gmail.com>

content/docs/usage/ingress.md

@@ -134,6 +134,10 @@ trigger Certificate resources to be automatically created:
   configure `spec.privateKey.rotationPolicy` field to set the rotation policy of the private key for a Certificate.
   Valid values are `Never` and `Always`. If unset a rotation policy `Never` will be used.
 
+## Generate multiple certificates with multiple ingresses
+
+If you need to generate certificates from multiple ingresses make sure it has the issuer annotation.
+Besides the annotation, it is necessary that each ingress possess a unique `tls.secretName`
 
 ## Optional Configuration
 
@@ -165,8 +169,6 @@ In the above example, cert-manager will create `Certificate` resources that
 reference the `ClusterIssuer` `letsencrypt-prod` for all Ingresses that have a
 `kubernetes.io/tls-acme: "true"` annotation.
 
-Issuers configured via annotations have a preference over the default issuer. If a default issuer is configured via CLI flags and a `cert-manager.io/cluster-issuer` or `cert-manager.io/issuer` annotation also has been added to an Ingress, the created `Certificate` will refer to the issuer configured via annotation.
-
 For more information on deploying cert-manager, read the [installation
 guide](../installation/README.md).