Add and organize CoreOS links in bare metal

* Add CoreOS link in bare metal section
* Keep different CoreOS and Ubuntu links together

_data/guides.yml

@@ -219,10 +219,12 @@ toc:
         path: /docs/getting-started-guides/fedora/flannel_multi_node_cluster/
       - title: CentOS
         path: /docs/getting-started-guides/centos/centos_manual_config/
-      - title: Ubuntu
-        path: /docs/getting-started-guides/ubuntu/
+      - title: CoreOS
+        path: /docs/getting-started-guides/coreos
       - title: CoreOS with Calico
         path: /docs/getting-started-guides/coreos/bare_metal_calico/
+      - title: Ubuntu
+        path: /docs/getting-started-guides/ubuntu/
       - title: Ubuntu Nodes with Calico
         path: /docs/getting-started-guides/ubuntu-calico/
   - title: Portable Multi-Node Cluster

docs/getting-started-guides/index.md

@@ -106,6 +106,7 @@ These solutions are combinations of cloud provider and OS not covered by the abo
 - [Centos](/docs/getting-started-guides/centos/centos_manual_config)
 - [Ubuntu](/docs/getting-started-guides/ubuntu)
 - [Docker Multi Node](/docs/getting-started-guides/docker-multinode)
+- [CoreOS](/docs/getting-started-guides/coreos)
 
 #### Integrations