We’ve had plenty of discussions here at DCist about city cyclists (Magnificent or menace? Discuss.), but now Maryland is stepping up to slow down two-wheelers along one of the area’s most popular biking trails. According to the Post, officials at the Maryland-National Capital Park and Planning Commission will soon start installing signs limiting cycling speeds to 15 mph along a 5.5-mile stretch of the Capital Crescent trail from Bethesda to the District line. They say…