Use k8s more widely

Signed-off-by: Celeste Horgan <celeste@cncf.io>

content/en/docs/contribute/_index.md

@@ -1,6 +1,6 @@
 ---
 content_type: concept
-title: Contribute to Kubernetes docs
+title: Contribute to K8s docs
 linktitle: Contribute
 main_menu: true
 no_list: true
@@ -8,7 +8,7 @@ weight: 80
 card:
   name: contribute
   weight: 10
-  title: Start contributing
+  title: Start contributing to K8s
 ---
 
 <!-- overview -->

content/en/docs/home/_index.md

@@ -32,7 +32,7 @@ cards:
   button: "View Tutorials"
   button_path: "/docs/tutorials"
 - name: setup
-  title: "Set up a cluster"
+  title: "Set up a K8s cluster"
   description: "Get Kubernetes running based on your resources and needs."
   button: "Set up Kubernetes"
   button_path: "/docs/setup"
@@ -57,7 +57,7 @@ cards:
   button: Contribute to the docs
   button_path: /docs/contribute
 - name: release-notes
-  title: Release Notes
+  title: K8s Release Notes
   description: If you are installing Kubernetes or upgrading to the newest version, refer to the current release notes.
   button: "Download Kubernetes"
   button_path: "/docs/setup/release/notes"