[util] Make clusters work with char offset instead of UTF-8 offset
This means the --features indices also refer to char position
instead of byte position now. Same for cluster values reported
by hb-shape.
Will add an option for byte indices later.
diff --git a/util/options.cc b/util/options.cc
index c2d4ec9..c394fd5 100644
--- a/util/options.cc
+++ b/util/options.cc
@@ -404,8 +404,11 @@
" Comma-separated list of font features to apply to text\n"
"\n"
" Features can be enabled or disabled, either globally or limited to\n"
- " specific byte ranges. The format is Python-esque. Here is how it all\n"
- " works:\n"
+ " specific character ranges. The range indices refer to the positions\n"
+ " between Unicode characters. The position before the first character\n"
+ " is 0, and the position after the first character is 1, and so on.\n"
+ "\n"
+ " The format is Python-esque. Here is how it all works:\n"
"\n"
" Syntax: Value: Start: End:\n"
"\n"
