Troubleshooting suggestion: beware including bash aliases

- [x] I have fzf 0.23.0 or above
- [x] I have read through https://github.com/junegunn/fzf.vim/blob/master/README.md
- [x] I have read through https://github.com/junegunn/fzf/blob/master/README-VIM.md
- [x] I have read through the manual page of fzf (`man fzf`)
- [x] I have searched through the existing issues

The [fzf wiki](https://github.com/junegunn/fzf/wiki/Examples#changing-directory) suggests an alias to `fd` which might interfere with `:FZF` and `:Files` if vim is configured to include that alias and if `$FZF_DEFAULT_COMMAND` uses `fd` or `fdfind` (which is also [suggested](https://github.com/junegunn/fzf#environment-variables) by the fzf readme).

The way this issue manifests is as the plugin working correctly but showing no file matches in the preview window / apparently finding no files. The quick fix is to remove or rename the alias.

I'm writing this issue to a) suggest that this be pointed out somewhere (only since some potential causes are suggested by fzf) and b) provide a search result for people who might run into the issue in the future.

Thanks for all your excellent work on this and other projects!