Update notes for v1.1.5

[p]Truck City v1.1.5 has just been released. This changelog also includes changes made in v1.1.4:[/p]

• [p]Improvement: performance improvement on research center lighting. The previous method may cause severe framerate drops on very big (hundreds of production buildings) research centers[/p]
• [p]Improvement: one-way roads directionality algorithm improved[/p]
• [p]Improvement: factory information tooltip text minor improvements[/p]
• [p]Bugfix: copy-pastig one-way road blueprints may cause the wrong tile to be pasted[/p]