Update rpc_demo description

rpc_demo.c file creates firmware that runs on remote processor. The current description implies that proxy service is implemented on remote side which is not true. Fix description and explicitly mention that proxy service is implemented on host side.

apps/examples/rpc_demo/rpc_demo.c

@@ -3,9 +3,9 @@
  */
 
 /*
- * This is a sample demonstration application that showcases usage of proxy from the remote core.
- * This application is meant to run on the remote CPU running baremetal.
- * This application can print to the host console and perform file I/O using proxy mechanism.
+ * This sample code demonstrates how to use file system of host processor using proxy mechanism.
+ * Proxy service is implemented on host processor. This application can print to the host console,
+ * take input from host console and perform regular file I/O such as open, read, write and close.
  */
 
 #include <stdio.h>