Issue 12293 - forward is missing from std.algorithm's cheat-sheet

https://issues.dlang.org/show_bug.cgi?id=12293

<del>Honestly I think `forward` doesn't belong in `std.algorithm`. It should likely belong to `std.functional` or a similar place. Hence why I had to add a "utility" category. I'd rather we just move the template out of std.algorithm though.</del>