### What it does
Checks for usage of unicode scripts other than those explicitly allowed
by the lint config.

This lint doesn't take into account non-text scripts such as `Unknown` and `Linear_A`.
It also ignores the `Common` script type.
While configuring, be sure to use official script name [aliases] from
[the list of supported scripts][supported_scripts].

See also: [`non_ascii_idents`].

[aliases]: http://www.unicode.org/reports/tr24/tr24-31.html#Script_Value_Aliases
[supported_scripts]: https://www.unicode.org/iso15924/iso15924-codes.html

### Why is this bad?
It may be not desired to have many different scripts for
identifiers in the codebase.

Note that if you only want to allow plain English, you might want to use
built-in [`non_ascii_idents`] lint instead.

[`non_ascii_idents`]: https://doc.rust-lang.org/rustc/lints/listing/allowed-by-default.html#non-ascii-idents

### Example
```
// Assuming that `clippy.toml` contains the following line:
// allowed-locales = ["Latin", "Cyrillic"]
let counter = 10; // OK, latin is allowed.
let счётчик = 10; // OK, cyrillic is allowed.
let zähler = 10; // OK, it's still latin.
let カウンタ = 10; // Will spawn the lint.
```