fish: Enable wayland support in firefox by default

See https://github.com/swaywm/sway/wiki/Running-programs-natively-under-wayland.

fish/.config/fish/config.fish

@@ -6,6 +6,7 @@ export EDITOR='nvim'
 export BROWSER='firefox'
 export MANPAGER='nvim +Man!'
 export NIX_SSL_CERT_FILE='/etc/ssl/certs/ca-certificates.crt'
+export MOZ_ENABLE_WAYLAND=1
 
 alias b="cd .."
 alias c="clear"