docs(README): add FreeBSD to Installation header (#213)

README.md

@@ -37,6 +37,7 @@ You can download and install a [prebuilt binary here](https://nightly.link/ayntg
 ### Package managers
 
 - [Arch Linux](https://aur.archlinux.org/packages/discordo-git/): `yay -S discordo-git` (thanks to [Alyxia Sother](https://github.com/lexisother) for maintaining the AUR package).
+- [FreeBSD](https://www.freshports.org/net-im/discordo): `pkg install discordo` or via the ports system `make -C /usr/ports/net-im/discordo install clean`.
 
 ### Building from source