added dark theme logo

Author: MarkMelotto

book/_config.yml

@@ -23,7 +23,7 @@ sphinx:                                              # Options passed on to the
       logo:
         text: Getting Started with eWaterCycle                               # Replace this with your own book title
         image_light: figures/ewatercycle_logo.png            # Put your logo for the light mode here (can be the same as image_dark)
-        image_dark: figures/ewatercycle_logo.png     # Put your logo for the dark mode here (can be the same as image_light)
+        image_dark: figures/ewatercycle_logo_dark.png     # Put your logo for the dark mode here (can be the same as image_light)
       repository_url: https://github.com/eWaterCycle/getting-started" # Add your own repo URL here
       path_to_docs: "book"                           # Required for edit_page_button, should be book if you're using TeachBooks package (https://github.com/TeachBooks/TeachBooks) or the TeachBooks deploy book workflow (https://teachbooks.io/manual/external/deploy-book-workflow/README.html)
       repository_branch: "main"                      # Replace when you change the name of your published branch (required for edit_page_button)