Add documentation for "less" LESSUTFCHARDEF (Private Use Area characters definition) option
- [x] I have searched the [issues](https://github.com/ryanoasis/nerd-fonts/issues) for my request and found nothing related and/or helpful
- [x] I have searched the [FAQ](https://github.com/ryanoasis/nerd-fonts/wiki/FAQ-and-Troubleshooting) for help
- [x] I have searched the [Wiki](https://github.com/ryanoasis/nerd-fonts/wiki) for help

**Issue**

On Linux,[less](https://github.com/gwsw/less), the most common pager, will no longer print Private Use Area characters by default.
I don't know when the transition took place, the version present in the Debian testing repositories  (590) does still display Nerd-fonts characters, but the compiled master (633) no longer displays them.

A [commit](https://github.com/gwsw/less/commit/dc4fa8c8c47dce999b9fdbd841f16b503b7d8632) dated September 25, 2022 introduces a new option (`LESSUTFCHARDEF`) that allows you to declare the type of character display according to the code points range.

Using this option to declare [code points listed in the wiki](https://github.com/ryanoasis/nerd-fonts/wiki/Glyph-Sets-and-Code-Points) with the last version force less to display Nerd-fonts characters.

``` bash
export LESSUTFCHARDEF=23fb-23fe:p,2665:p,26a1:p,2b58:p,e000-e00a:p,e0a0-e0a2:p,e0a3:p,e0b0-e0b3:p,e0b4-e0c8:p,e0ca:p,e0cc-e0d4:p,e200-e2a9:p,e300-e3e3:p,e5fa-e6a6:p,e700-e7c5:p,ea60-ebeb:p,f000-f2e0:p,f300-f32f:p,f400-f532:p,f500-fd46:p,f0001-f1af0:p
```

**Solution**

I think that instructions to export the correct variable should be given to Nerd-fonts users in the wiki or the readme.

**Other**

![image](https://github.com/ryanoasis/nerd-fonts/assets/45816387/95389823-a451-4a90-8d64-5002d69755ed)

