Add help text for 'uniq -i'

Signed-off-by: Jody Bruchon <jody@jodybruchon.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

coreutils/uniq.c

@@ -26,6 +26,7 @@
 //usage:     "\n	-c	Prefix lines by the number of occurrences"
 //usage:     "\n	-d	Only print duplicate lines"
 //usage:     "\n	-u	Only print unique lines"
+//usage:     "\n	-i	Ignore case"
 //usage:     "\n	-f N	Skip first N fields"
 //usage:     "\n	-s N	Skip first N chars (after any skipped fields)"
 //usage:     "\n	-w N	Compare N characters in line"