doc: Fix broken link in README

Arch Linux recently merged all entries in its 'community' repository
into 'extra' (https://archlinux.org/news/git-migration-announcement/).
This commit updates the README to reflect this change.

README.md

@@ -199,7 +199,7 @@ scoop install fq
 
 ### Arch Linux
 
-`fq` can be installed from the [community repository](https://archlinux.org/packages/community/x86_64/fq/) using [pacman](https://wiki.archlinux.org/title/Pacman):
+`fq` can be installed from the [extra repository](https://archlinux.org/packages/extra/x86_64/fq/) using [pacman](https://wiki.archlinux.org/title/Pacman):
 
 ```sh
 pacman -S fq