add new intro para to auth doc
add new intro para to auth doc

AndyHuu/flocker,agonzalezro/flocker,achanda/flocker,wallnerryan/flocker-profiles,mbrukman/flocker,w4ngyi/flocker,moypray/flocker,wallnerryan/flocker-profiles,wallnerryan/flocker-profiles,moypray/flocker,mbrukman/flocker,adamtheturtle/flocker,agonzalezro/flocker,achanda/flocker,mbrukman/flocker,adamtheturtle/flocker,achanda/flocker,AndyHuu/flocker,w4ngyi/flocker,agonzalezro/flocker,adamtheturtle/flocker,hackday-profilers/flocker,AndyHuu/flocker,hackday-profilers/flocker,hackday-profilers/flocker,w4ngyi/flocker,moypray/flocker