Use fd for fzf if available on system

fd is orders of magnitude faster when searching for files. This patch
will force fzf to use fd instead of find.

This change is implemented per the recommendation:
https://github.com/junegunn/fzf#environment-variables

plugins/available/fzf.plugin.bash

@@ -6,6 +6,8 @@ about-plugin 'load fzf, if you are using it'
 
 [ -f ~/.fzf.bash ] && source ~/.fzf.bash
 
+command -v fd &> /dev/null && export FZF_DEFAULT_COMMAND='fd --type f'
+
 fe() {
   about "Open the selected file in the default editor"
   group "fzf"