Add note for zsh users that recommends sourcing nvm before using it (#2007)
Add note for zsh users that recommends sourcing nvm before using it (#2007)


PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs