Minor edit

docs/Proportional-Interval-Stamp/Proportional-Interval-Stamp.mdx

@@ -181,7 +181,7 @@ $$
 \Delta n = \frac{\Delta x}{\eta r(x)}
 $$
 
-To find the number of stamps $\Delta n$ over the edge, integrate $\Delta n$ from 0 to x.
+To find the number of stamps $n(x)$ from zero to a point at x, integrate $\Delta n$ from 0 to x.
 
 $$
 n(x) = \int_0^{x} \frac{dx}{\eta r(x)}