docs: fix typo

Signed-off-by: Carlos Alexandro Becker <caarlos0@users.noreply.github.com>

progress/progress.go

@@ -309,7 +309,7 @@ func (m Model) barView(b *strings.Builder, percent float64, textWidth int) {
 			if fw == 1 {
 				// this is up for debate: in a gradient of width=1, should the
 				// single character rendered be the first color, the last color
-				// or exactly 50% inbetween? I opted for 50%
+				// or exactly 50% in between? I opted for 50%
 				p = 0.5
 			} else if m.scaleRamp {
 				p = float64(i) / float64(fw-1)