Update cordova-preparation.md (#625)
Update cordova-preparation.md (#625)

* Update cordova-preparation.md

You have to first switch into the cordova project folder. Otherwise the command fails with "Current working directory is not a Cordova-based project."

Also fixed reference to previous step numbers in 4.

* Update cordova-preparation.md

Fixed minor grammar mistake.

rstoenescu/quasar-site,quasarframework/quasar-framework.org,quasarframework/quasar-framework.org,rstoenescu/quasar-site,rstoenescu/quasar-site,quasarframework/quasar-framework.org