Fix docs referencing outdated React Router <Link> API (#1523)
Fix docs referencing outdated React Router <Link> API (#1523)


Khaledgarbaya/gatsby,chiedo/gatsby,danielfarrell/gatsby,danielfarrell/gatsby,ChristopherBiscardi/gatsby,gatsbyjs/gatsby,danielfarrell/gatsby,ChristopherBiscardi/gatsby,chiedo/gatsby,fabrictech/gatsby,fabrictech/gatsby,gatsbyjs/gatsby,ChristopherBiscardi/gatsby,gatsbyjs/gatsby,fk/gatsby,Khaledgarbaya/gatsby,0x80/gatsby,fk/gatsby,ChristopherBiscardi/gatsby,0x80/gatsby,mickeyreiss/gatsby,mingaldrichgan/gatsby,gatsbyjs/gatsby,mickeyreiss/gatsby,fabrictech/gatsby,chiedo/gatsby,0x80/gatsby,mickeyreiss/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,fk/gatsby,Khaledgarbaya/gatsby,mingaldrichgan/gatsby,mingaldrichgan/gatsby