Acknowledge the source of nightshot_iso_100.bmp

git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@903 632fc199-4ca6-4c93-a231-07263d6284db
2013-01-13 11:30:12 +00:00 · 2013-01-13 11:30:12 +00:00 · c5052c7701
--- a/testimages/nightshot_iso_100.txt
+++ b/testimages/nightshot_iso_100.txt
@ -0,0 +1,2 @@
+This image was extracted from the 8-bit nightshot_iso_100 image available at
+http://www.imagecompression.info/test_images/