Fix markdown files according to markdownlint recommendations

There are some issues and quirks in the markdown documentation files
suggested by the markdownlint project checker that might benefit from
being fixed, which this patch does.

Change-Id: I33245825e5bb543b5ce1732204984d4a0b169668
Signed-off-by: Joakim Roubert <joakimr@axis.com>

README.md

@@ -1,6 +1,6 @@
-# Build a Kubernetes cluster using k3s via Ansible.
+# Build a Kubernetes cluster using k3s via Ansible
 
-Author: https://github.com/itwars
+Author: <https://github.com/itwars>
 
 ## K3s Ansible Playbook
 
@@ -16,7 +16,7 @@ on processor architecture:
 - [X] arm64
 - [X] armhf
 
-## System requirements:
+## System requirements
 
 Deployment environment must have Ansible 2.4.0+
 Master and nodes must have passwordless SSH access
@@ -25,7 +25,7 @@ Master and nodes must have passwordless SSH access
 
 Add the system information gathered above into a file called hosts.ini. For example:
 
-```
+```bash
 [master]
 192.16.35.12
 
@@ -35,14 +35,20 @@ Add the system information gathered above into a file called hosts.ini. For exam
 [k3s-cluster:children]
 master
 node
+
 ```
 
 Start provisioning of the cluster using the following command:
 
-```
+```bash
 ansible-playbook site.yml -i inventory/hosts.ini
 ```
 
 ## Kubeconfig
 
-To get access to your **Kubernetes** cluster just scp debian@master_pi:~/kube/config ~/.kube/config
+To get access to your **Kubernetes** cluster just
+
+```bash
+scp debian@master_pi:~/kube/config ~/.kube/config
+```
+