Fix navigation when going from styleguide homepage to layout subcomponent.
Fix navigation when going from styleguide homepage to layout
subcomponent.

[ReFinishes #78510872]

Signed-off-by: Jenn Dodd <6f2d274da909b880cd01c918ca29f96e2eff74de@pivotal.io>

pivotal-cf/pivotal-ui,npm/pivotal-ui,sjolicoeur/pivotal-ui,pivotal-cf/pivotal-ui,pivotal-cf/pivotal-ui,CanopyCloud/pivotal-ui,npm/pivotal-ui,CanopyCloud/pivotal-ui,CanopyCloud/pivotal-ui,sjolicoeur/pivotal-ui,npm/pivotal-ui,sjolicoeur/pivotal-ui,sjolicoeur/pivotal-ui