Fixed overlay error in episode 9 between state and country boundary

Relayered so state is above and country is below. The county layer needs an alpha so the states show up. Also made the state boundaries lighter so it pops out more compared to the country boundary, and I made the country boundary black to increase the contrast.

Author: kristi-sara

episodes/09-vector-when-data-dont-line-up-crs.Rmd

@@ -141,8 +141,8 @@ boundaries and country boundaries.
 
 ```{r us-boundaries-thickness}
 ggplot() +
-  geom_sf(data = country_boundary_US, color = "gray18", size = 2) +
-  geom_sf(data = state_boundary_US, color = "gray40") +
+  geom_sf(data = state_boundary_US, color = "gray60") +
+  geom_sf(data = country_boundary_US, color = "black",alpha = 0.25,size = 5)
   ggtitle("Map of Contiguous US State Boundaries") +
   coord_sf()
 ```