pop3-stat.c: Corrected small typo from commit 91d62e9a

#include <stdio.h>

#include <curl/curl.h>

/* This is a simple example showing how to ontain message statistics using

/* This is a simple example showing how to obtain message statistics using

 * libcurl's POP3 capabilities.

 *

 * Note that this example requires libcurl 7.26.0 or above.