Template Example needs updates

[Davido264]

On the last update, harmonized_colors was reworked into custom_colors. So the new way to define harmonized_colors in templates is:

# config
[config.custom_colors]
red = "#fb4934"

{{colors.red.default.hex}}

Where the previous way to define it was:

# config
[config.colors_to_harmonize]
red = "#fb4934"

{{harmonized_colors.red.hex}}

However, the template example gave in example/colors.whatever-extension, stills show the previous way to define templates. It should be updated to the new one

Edit: The config in example/config.toml is updated, the change is only required in example/colors.whatever-extension,