Make podSubnet consistent across install guide

In the Install Kind page (https://docs.cilium.io/en/v1.8/gettingstarted/kind/),
we properly quote the podSubnet as according to the
[kind config page](https://kind.sigs.k8s.io/docs/user/configuration/). However,
later in the guide, we don't quote the podSubnet, leaving a user with
inconsistent configurations. Making quotes standard.

Signed-off-by: Jed Salazar <jed@isovalent.com>

Documentation/gettingstarted/kind.rst

@@ -99,8 +99,8 @@ Example ``kind-cluster1.yaml``:
     - role: worker
     networking:
       disableDefaultCNI: true
-      podSubnet: 10.0.0.0/16
-      serviceSubnet: 10.1.0.0/16
+      podSubnet: "10.0.0.0/16"
+      serviceSubnet: "10.1.0.0/16"
 
 Example ``kind-cluster2.yaml``:
 
@@ -115,8 +115,8 @@ Example ``kind-cluster2.yaml``:
     - role: worker
     networking:
       disableDefaultCNI: true
-      podSubnet: 10.2.0.0/16
-      serviceSubnet: 10.3.0.0/16
+      podSubnet: "10.2.0.0/16"
+      serviceSubnet: "10.3.0.0/16"
 
 Create Kind Clusters
 --------------------