Update 11_nearly_free_electron_model.md

colors were changed in the figure, but not in the text referring to the figure

src/11_nearly_free_electron_model.md

@@ -89,7 +89,7 @@ ax.set_xticklabels(fr"${i}\pi$".replace("1", "") if i else "$0$" for i in range(
 draw_classic_axes(ax, xlabeloffset=4)
 ```
 
-In this figure, the red curves represent the nearly-free electron dispersion, which differs from the free-electron dispersion (black curves) because of the interaction with the lattice. We see that **band gaps** open where two copies of the free-electron dispersion cross. A key goal of this lecture is to understand how the weak interaction with the lattice leads to this modified band structure.
+In this figure, the orange curves represent the nearly-free electron dispersion, which differs from the free-electron dispersion (blue curves) because of the interaction with the lattice. We see that **band gaps** open where two copies of the free-electron dispersion cross. A key goal of this lecture is to understand how the weak interaction with the lattice leads to this modified band structure.
 
 ### Analyzing the avoided crossings