Update link to "installing" documentation
Update link to "installing" documentation

The link was broken, probably pointing to an old url.
AndyHuu/flocker,AndyHuu/flocker,mbrukman/flocker,mbrukman/flocker,wallnerryan/flocker-profiles,hackday-profilers/flocker,wallnerryan/flocker-profiles,AndyHuu/flocker,hackday-profilers/flocker,w4ngyi/flocker,w4ngyi/flocker,w4ngyi/flocker,hackday-profilers/flocker,mbrukman/flocker,wallnerryan/flocker-profiles