chore: support external cert-manager

docs/content/en/docs/install/cert-manager.md

@@ -14,19 +14,18 @@ without the overhead of other cert-managers.
 For a description of the architecture, see
 [Keptn Certificate Manager](../concepts/architecture/cert-manager.md).
 
-KLT, however, works well with standard cert-managers.
-The KLT cert-manager can also coexist with another cert-manager.
-If you are already using a different cert-manager,
-you can continue to use that cert-manager for other components
+KLT also works well with the `cert-manager.io`.
+If you are already `cert-manager.io`,
+you can continue to use it for other components
 and use the KLT cert-manager just for KLT activities
-or you can configure KLT to use that cert-manager.
+or you can disable the KLT cert-manager
+and configure KLT to use `cert-manager.io`.
 
-If you want KLT to use your cert-manager,
+If you want KLT to use `cert-manager.io`,
 you must configure it *before* you install KLT.
 The steps are:
 
-* Install the cert-manager of your choice
-  if it is not already installed.
+* Install the `cert-manager.io` if it is not already installed.
 * Add the `Certificate` and `Issuer` CRs for `cert-manager.io`.
 * (optional) Install Keptn without the built-in `klt-cert-manager` via Helm