docs: use indigo color scheme for dark mode (#34145)

Author: RahulGautamSingh

tools/mkdocs/mkdocs.yml

@@ -91,8 +91,8 @@ theme:
       toggle:
         icon: material/weather-sunny
         name: Switch to system preference
-      primary: 'teal'
-      accent: 'teal'
+      primary: 'indigo'
+      accent: 'indigo'
 
   features:
     # Navigation pruning (not compatible with navigation.expand)