Include fontconfig .conf in Symbols Only release
### Requirements

- [X] I have searched the [issues](https://github.com/ryanoasis/nerd-fonts/issues) for my request and found nothing related or helpful
- [X] I have checked the [FAQ](https://github.com/ryanoasis/nerd-fonts/wiki/FAQ-and-Troubleshooting) for help
- [X] I have reviewed the [Wiki](https://github.com/ryanoasis/nerd-fonts/wiki) for relevant information

### Problem Description

The release package for the Symbols Only Nerd Font contains readme and license, and the fixed and propo TTFs.

A very useful file in the repository here to go along with those files, is https://github.com/ryanoasis/nerd-fonts/blob/-/10-nerd-font-symbols.conf

I thought it might be nice to put that file in the release along with the TTFs. This would have the benefit of allowing packagers to ensure that the fallback works on their distro, and allowing users to more easily select between the two font variants.

### Desired Solution

Package https://github.com/ryanoasis/nerd-fonts/blob/-/10-nerd-font-symbols.conf with Symbols-Only release

### Alternatives Considered

Download it myself

### Additional Context

Installing my distro (Tumbleweed) package of the symbols-only Nerd Font, installs both TTFs, without any configuration, as per the release. The distro default config is good, and fallback immediately works. However, fontconfig prefers the monospaced variant unless directed otherwise, such as by the abovementioned config file. It's nice to have the full experience, out of the box. For now, I get there with:
```
cd /etc/fonts/conf.d/
sudo wget https://raw.githubusercontent.com/ryanoasis/nerd-fonts/master/10-nerd-font-symbols.conf
sudo restorecon -rvF 10-nerd-font-symbols.conf (selinux requirement)
fc-cache -rv
```
So this is not too hard to deal with, but it would be nice if it "just works" :)

Thanks for an excellent font!