Fix remux example to take correct main() params

Also add comments explaining the program and the videostreamer lib.

cmd/remux_example/remux_example.c

@@ -1,11 +1,15 @@
+//
+// This program remuxes from a given RTSP input to an mp4 container.
+//
+
 #include <stdbool.h>
 #include <stdio.h>
 #include <videostreamer.h>
 
-int main(const int argc, const char * const argv)
+int main(const int argc, const char * const * const argv)
 {
 	if (argc != 2) {
-		printf("Usage: %s <rtsp URL>\n", argv[0]);
+		printf("Usage: %s <RTSP URL>\n", argv[0]);
 		return 1;
 	}
 

videostreamer.c

@@ -1,4 +1,10 @@
 //
+// This library provides remuxing from a video stream (such as an RTSP
+// URL) to an MP4 container. It writes a fragmented MP4 so that it can be
+// streamed to a pipe.
+//
+// There is no re-encoding. The stream is copied as is.
+//
 // The logic here is heavily based on remuxing.c by Stefano Sabatini.
 //
 
@@ -14,7 +20,6 @@ static void
 __vs_log_packet(const AVFormatContext * const,
 		const AVPacket * const, const char * const);
 
-
 void
 vs_setup(void)
 {