Add a paragraph about stopping the application to the general points of hiring process.

Open Marin Jankovski requested to merge applicant_can_stop into master

I'm informing applicants that go through Build Engineer pipeline that they can stop the application and return when they feel ready. Maybe this should be part of our process.

/cc @sytses @Vatalidis @stanhu @smcgivern @DouweM @pcarranza