fix: use yml in markdown (#27)

10-secrets/README.md

@@ -26,7 +26,7 @@ You can reference a secret from a pod, either per env variable or mounting a vol
 
 Here we mount the secret `mysecret` to the path `/etc/foo` inside the pod:
 
-```yaml
+```yml
 apiVersion: v1
 kind: Pod
 metadata:
@@ -48,7 +48,7 @@ spec:
 Here we bind the value `username` from the secret `mysecret` to the env variable `SECRET_USERNAME`,
 `password` from the secret `mysecret` to the env variable `SECRET_PASSWORD`:
 
-```yaml
+```yml
 apiVersion: v1
 kind: Pod
 metadata:

11-probes/README.md

@@ -26,7 +26,7 @@ Both liveness and readiness probes have the same configuration. You have three w
 
 The `exec` probe let you configure a command that Kubernetes will run in your container. If the command exits with a non zero status the probe will be considered unhealthy:
 
-```yaml
+```yml
 livenessProbe:
   exec:
     command:
@@ -43,7 +43,7 @@ We will see later what `initialDelaySeconds` and `periodSeconds` means.
 
 The `http` probe let you configure a HTTP endpoint that Kubernetes will call in your container. If this endpoint returns a non 2XX status the probe will be considered unhealthy:
 
-```yaml
+```yml
 livenessProbe:
   httpGet:
     path: /healthz
@@ -65,7 +65,7 @@ The `http` probe has two mandatory fields `path` and `port` and one optional `ht
 
 The `tcp` probe let you configure a TCP port that Kubernetes will try to connect to. If it does not manage to establish a connection the probe will be considered unhealthy:
 
-```yaml
+```yml
 livenessProbe:
   tcpSocket:
     port: 8080
@@ -81,7 +81,7 @@ The `periodSeconds` field specifies that Kubernetes should perform the probe eve
 
 If we take the example:
 
-```yaml
+```yml
 livenessProbe:
   httpGet:
     path: /healthz

13-affinity-anti-affinity/README.md

@@ -20,7 +20,7 @@ Hinting Kubernetes to run multiple pods on different nodes is a good way to impr
 
 The `affinity` is specified at the pod level. The configuration for `podAffinity` or `podAntiAffinity` is the same. So let's look at a `podAntiAffinity`.
 
-```yaml
+```yml
 apiVersion: v1
 kind: Pod
 metadata:
@@ -56,7 +56,7 @@ In english words, this configuration means that we want to ensure that pods with
 
 You also have `preferredDuringSchedulingIgnoredDuringExecution` to not require but only hints the scheduler. Carefull the configuration for this is different:
 
-```yaml
+```yml
 apiVersion: v1
 kind: Pod
 metadata:
@@ -115,7 +115,7 @@ Here we add the label `gpu` with value `yes` to the node `node1`.
 
 You can force a pod to be scheduled on a specific node by adding right `nodeAffinity` to the spec of it. Here we would like to pod to be scheduled on a node with the label `gpu=yes`
 
-```yaml
+```yml
 apiVersion: v1
 kind: Pod
 metadata:

14-pdb/README.md

@@ -12,7 +12,7 @@ Defining a “Pod Disruption Budget” helps Kubernetes manage your pods when a
 
 A `PDB` is configured as this:
 
-```yaml
+```yml
 apiVersion: policy/v1beta1
 kind: PodDisruptionBudget
 metadata:

15-hpa-vpa/README.md

@@ -6,7 +6,7 @@ HPA means `Horizontal Pod Autoscaler`. It automatically scales the number of pod
 
 Let's take an example with CPU usage:
 
-```yaml
+```yml
 apiVersion: autoscaling/v1
 kind: HorizontalPodAutoscaler
 metadata:
@@ -101,7 +101,7 @@ kubectl apply -f examples/hamster.yaml
 
 Look at the file [hamster.yaml](https://github.com/kubernetes/autoscaler/tree/master/vertical-pod-autoscaler/examples). It contains the VPA definition:
 
-```yaml
+```yml
 apiVersion: "autoscaling.k8s.io/v1beta2"
 kind: VerticalPodAutoscaler
 metadata:

17-volumes/README.md

@@ -20,7 +20,7 @@ Let's create the volume where our mysql data will be stored.
 
 First we create the `PersistentVolume`. It is a piece of storage in the cluster that has been provisioned by a cluster administrator. It is a resource in the cluster just like a node is a resource of the cluster.
 
-```yaml
+```yml
 apiVersion: v1
 kind: PersistentVolume
 metadata:

18-stateful-set/README.md

@@ -53,7 +53,7 @@ Like a `Deployment`, a `StatefulSet` manages Pods that are based on an identical
 * Ordered, graceful deployment and scaling
 * Ordered, automated rolling updates, ex: MySQL Master+Slave
 
-```yaml
+```yml
 apiVersion: apps/v1
 kind: StatefulSet
 metadata: