rpc_demo: fix spelling and grammar in code comment

There were some minor typos in the top level comment
block for the rpc_demo.c example.

Signed-off-by: Michael Bullis <mcbullisisu@gmail.com>

apps/examples/rpc_demo/rpc_demo.c

@@ -4,7 +4,7 @@
 
 /* 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 applicationr can print to to master console and perform file I/O using proxy mechanism. */
+ This application can print to the master console and perform file I/O using proxy mechanism. */
 
 #include <stdio.h>
 #include <string.h>