Always pull latest cert-manager version (#407)

* Always pull latest cert-manager version

Make sure we're always pulling the latest cert-manager

* Added clarity on cert-manager pinned version and latest

* Fix typo in URL

docs/quickstart/installing-thundernetes.md

@@ -13,10 +13,24 @@ Follow the steps below to install Thundernetes on your Kubernetes cluster.
 
 Once you have a Kubernetes cluster up and running, you need to install [cert-manager](https://cert-manager.io). Cert-manager is a certificate controller for Kubernetes and it is needed for the webhooks used to validate your GameServerBuilds.
 
+The following will install `cert-manager` v1.8.0:
+
 {% include code-block-start.md %}
 kubectl apply -f https://github.com/cert-manager/cert-manager/releases/download/v1.8.0/cert-manager.yaml
 {% include code-block-end.md %}
 
+If you feel adventurous, you may try installing the latest version of `cert-manager`, however there are no guarantees in this case. Thundernetes install is only tested against the pinned version.
+
+{% include code-block-start.md %}
+# Get the latest cert-manager release version number
+VERSION=$(curl -s https://api.github.com/repos/cert-manager/cert-manager/releases/latest \
+    | grep '"tag_name":' \
+    | sed -E 's/.*"([^"]+)".*/\1/')
+
+# Install latest cert-manager
+kubectl apply -f https://github.com/cert-manager/cert-manager/releases/download/$VERSION/cert-manager.yaml
+{% include code-block-end.md %}
+
 To verify that cert-manager is installed, you can run the following command:
 
 {% include code-block-start.md %}
@@ -80,4 +94,4 @@ Then, you can run the following script to install Thundernetes with TLS security
 kubectl apply -f https://github.com/PlayFab/thundernetes/main/installfiles/operator_with_security.yaml
 {% include code-block-end.md %}
 
-**Note:** The two installation files (operator.yaml and operator_with_security.yaml) are identical except for the API_SERVICE_SECURITY environment variable that is passed into the controller container.
+**Note:** The two installation files (operator.yaml and operator_with_security.yaml) are identical except for the API_SERVICE_SECURITY environment variable that is passed into the controller container.