Fix avifStream comment in internal.h

[skip ci]

include/avif/internal.h

diff --git a/include/avif/internal.h b/include/avif/internal.h
index ff01e45..c5dce33 100644
--- a/include/avif/internal.h
+++ b/include/avif/internal.h
@@ -366,7 +366,9 @@
 void avifDiagnosticsPrintf(avifDiagnostics * diag, const char * format, ...);
 
 // ---------------------------------------------------------------------------
-// avifStream (network byte order; big-endian unless specified)
+// avifStream
+//
+// In network byte order (big-endian) unless otherwise specified.
 
 typedef size_t avifBoxMarker;