net: correct the description of ip_to_string()

The output of ip_to_string() is a string.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
diff --git a/include/net-common.h b/include/net-common.h
index 8fc1bac..29d31f3 100644
--- a/include/net-common.h
+++ b/include/net-common.h
@@ -427,7 +427,7 @@
 struct in_addr string_to_ip(const char *s);
 
 /**
- * ip_to_string() - Convert a string to ip address
+ * ip_to_string() - Convert an IPv4 address to a string
  *
  * Implemented in lib/net_utils.c (built unconditionally)
  *