Demo update notes for v0.39

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

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

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