Add advise about fpath to Writing_Plugins.md
Add advise about fpath to Writing_Plugins.md

All files in the fpath directories should be able to be compiled. See
http://zsh.sourceforge.net/Doc/Release/User-Contributions.html#Recompiling-Functions

This allows ZSH to take advantage of compiled function digest files. See
http://zsh.sourceforge.net/Doc/Release/Functions.html#Autoloading-Functions

voronkovich/awesome-zsh-plugins,unixorn/awesome-zsh-plugins