[Development] Upcoming CI disruptions

[Rohan McGovern]

In preparation for the transfer of remaining systems from Nokia to
Digia, various projects covered by the Qt CI will soon be migrated from
Nokia's Pulse infrastructure to a new Jenkins setup.

The migration will begin tomorrow. The first projects to be migrated
will be QA-related projects (dogfooding). Assuming no showstoppers
occur, the migration will continue next week.

In theory, there should be very few user-visible differences from the
migration.  Changes may be staged as usual.  However, please be aware of
a higher than normal risk of disruptions during this time.