Update theme reference

Signed-off-by: Emmanuel Ferdman <[email protected]>

docs/THEMES.md

@@ -41,7 +41,7 @@ Themes are just css files with a header identifying them as a theme:
 }
 ```
 
-You can modify all classes and use all kind of css, but we recommend using the css variables set by [`themes/_themebase.scss`](https://github.com/deltachat/deltachat-desktop/blob/main/themes/_themebase.scss) as these are less likely to change between releases and thus a bit more stable, but in general there are no stability gurantees for theming, so expect to be required to update your theme when you update to a new deltachat desktop version comes out.
+You can modify all classes and use all kind of css, but we recommend using the css variables set by [`themes/_themebase.scss`](https://github.com/deltachat/deltachat-desktop/blob/main/packages/frontend/themes/_themebase.scss) as these are less likely to change between releases and thus a bit more stable, but in general there are no stability gurantees for theming, so expect to be required to update your theme when you update to a new deltachat desktop version comes out.
 
 ## Setting a theme from CLI