Quadrant: One-Sided Axes
An axis with one label is drawn from the plot corner; a trailing `-->` keeps its arrow in the label.
quadrant-one-sided-axes.mmd
quadrantChart
x-axis Effort -->
y-axis Impact
quadrant-1 Big bets
quadrant-3 Fill-ins
Refactor: [0.8, 0.4]
Docs: [0.2, 0.3]