docs(readme): doc setting app-config for localhost demo
docs(readme): doc setting app-config for localhost demo

Running `uportal-app-framework` locally demos a lot better if you first configure it a bit. This change adds hints to README on what configuration to do.
paulerickson/uw-frame,paulerickson/uw-frame,UW-Madison-DoIT/uw-frame,uPortal-Project/uportal-app-framework,thevoiceofzeke/uw-frame,thevoiceofzeke/uw-frame,paulerickson/uw-frame,uPortal-Project/uportal-app-framework,UW-Madison-DoIT/uw-frame,UW-Madison-DoIT/uw-frame,uPortal-Project/uportal-app-framework,thevoiceofzeke/uw-frame