Document new component <OutboundLink> (#4787)
Document new component <OutboundLink> (#4787)

* Add OutBoundLink component to gatsby-plugin-google-analytics

* Track outbound links on gatsbyjs.org

* Fix link errors + handle other types of clicks

* Use named arguments

* Document new component <OutboundLink>

ChristopherBiscardi/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,mingaldrichgan/gatsby,0x80/gatsby,fk/gatsby,gatsbyjs/gatsby,fk/gatsby,0x80/gatsby,ChristopherBiscardi/gatsby,ChristopherBiscardi/gatsby,ChristopherBiscardi/gatsby,fk/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,mingaldrichgan/gatsby,mingaldrichgan/gatsby,0x80/gatsby,gatsbyjs/gatsby