Updated the CCSS notebook example based on the new structure

[igarousi]

Regarding Danielle's suggestion on replacing the map plot with the one Amy created, I believe plot_obs_locations() and plot_sites_within_domain() serve different purposes.

• plot_obs_locations() creates a static plot of observation locations using model grid indices with imshow() and scatter(). It does not use geographic coordinates or shapefiles, and it saves the output as a figure.
• In contrast, plot_sites_within_domain() uses geospatial coordinates, displays site markers over the watershed boundary, adds a basemap, and returns an interactive folium.Map object.
  Given these differences, I decided to keep plot_sites_within_domain() for this notebook, but I renamed the function name to map_sites_within_watershed() to better reflect its purpose.

[danielletijerina]

Looks great! I like the CCSS photo addition!