drop references to old net-cert-manager controller (#6333)

Author: dprotaso

docs/install/uninstall.md

@@ -33,20 +33,6 @@ Uninstall any Serving extensions you have installed by performing the steps in t
     kubectl delete -f {{ artifact( repo="serving", file="serving-hpa.yaml") }}
     ```
 
-
-
-=== "TLS with cert-manager"
-
-    1. Uninstall the component that integrates Knative with cert-manager:
-
-        ```bash
-        kubectl delete -f {{ artifact( repo="net-certmanager", file="release.yaml") }}
-        ```
-
-    1. Optional: if you no longer need cert-manager, uninstall it by following the steps in the
-    [cert-manager documentation](https://cert-manager.io/docs/installation/uninstall/kubernetes/).
-
-
 ### Uninstalling a networking layer
 
 Follow the relevant procedure to uninstall the networking layer you installed:

docs/serving/knative-kubernetes-services.md

@@ -44,7 +44,6 @@ that are active when running Knative Serving.
      activator                    1         1         1            1           1h
      autoscaler                   1         1         1            1           1h
      controller                   1         1         1            1           1h
-     net-certmanager-controller   1         1         1            1           1h
      net-istio-controller         1         1         1            1           1h
      webhook                      1         1         1            1           1h
      ```
@@ -78,10 +77,6 @@ The webhook intercepts all Kubernetes API calls as well as all CRD insertions
 and updates. It sets default values, rejects inconsistent and invalid objects,
 and validates and mutates Kubernetes API calls.
 
-### Deployment: net-certmanager-controller
-
-The certmanager reconciles cluster ingresses into cert manager objects.
-
 ### Deployment: net-istio-controller
 
 The net-istio-controller deployment reconciles a cluster's ingress into an