Demo update notes for v0.39

Truck City v0.39-Demo has just been released. This is the change log:

• Feature: trucks can be configured so they pick up only some container types, instead of all

• Feature: clicking on the bottom right color band in the truck menu allows changing the truck's color
• Feature: clicking on the calendar icon at the top-right will show the leaderboard for the current map
• Balance: production rate decreased for stone mines and stone processing factories (cement factory and rock crusher)
• Improvement: container colors adjusted to make them more clearly different
• Improvement: some minor tile fixes in the DEMO mission map
• Improvement: translations improved for market menu
• Bugfix: fixed corner case where research center may stall