Updated _index.md to remove duplicate lines

Removed duplicate lines in the documentation.

Author: pankaj02

content/en/docs/reference/using-api/_index.md

@@ -31,13 +31,6 @@ For general background information, read
 describes how clients can authenticate to the Kubernetes API server, and how their
 requests are authorized.
 
-<!-- body -->
-
-The REST API is the fundamental fabric of Kubernetes. All operations and
-communications between components, and external user commands are REST API
-calls that the API Server handles. Consequently, everything in the Kubernetes
-platform is treated as an API object and has a corresponding entry in the
-API.
 
 ## API versioning