[Issue 21125] Typo in std.range.refRange documentation for opIndex

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=21125

--- Comment #1 from moonlightsentinel at disroot.org ---
See https://dlang.org/phobos/std_range.html#.RefRange.opIndex

--