Update scroll-directive.md (#252)
Update scroll-directive.md (#252)

External link to the v-scroll directive, making it clear that `v-scroll` does not exist in this project.
quasarframework/quasar-framework.org,rstoenescu/quasar-site,rstoenescu/quasar-site,quasarframework/quasar-framework.org,quasarframework/quasar-framework.org,rstoenescu/quasar-site