generate and update api reference to 1.15 (#15042)

* generate and update api reference to 1.15

* update ref page with v1.15 link

content/en/docs/reference/_index.md

@@ -20,11 +20,11 @@ This section of the Kubernetes documentation contains references.
 
 * [Kubernetes API Overview](/docs/reference/using-api/api-overview/) - Overview of the API for Kubernetes.
 * Kubernetes API Versions
+  * [1.15](/docs/reference/generated/kubernetes-api/v1.15/)
   * [1.14](/docs/reference/generated/kubernetes-api/v1.14/)
   * [1.13](/docs/reference/generated/kubernetes-api/v1.13/)
   * [1.12](/docs/reference/generated/kubernetes-api/v1.12/)
   * [1.11](/docs/reference/generated/kubernetes-api/v1.11/)
-  * [1.10](/docs/reference/generated/kubernetes-api/v1.10/)
 
 ## API Client Libraries
 

content/en/docs/reference/kubernetes-api/index.md

@@ -1,5 +1,5 @@
 ---
-title: v1.14
+title: v1.15
 ---
 
-[Kubernetes API v1.14](/docs/reference/generated/kubernetes-api/v1.14/)
+[Kubernetes API v1.15](/docs/reference/generated/kubernetes-api/v1.15/)