message: Update fish completion installation
diff: @@ -284,9 +284,11 @@ echo "source ~/.bash_completion/alacritty" >> ~/.bashrc
  To install the completions for fish, run
  ```
  -sudo cp alacritty-completions.fish $__fish_datadir/vendor_completions.d/alacritty.fish
  +sudo cp alacritty-completions.fish $__fish_data_dir/vendor_completions.d/alacritty.fish
  ```
  +**Note:** For fish versions below 3.0 `$__fish_datadir` must be used instead.
  +
  ## Terminfo
  The terminfo database contains entries describing the terminal
  