DEV: Update placeholder themeable site setting URLs (#69)

Author: martin-brennan

docs/05-themes-components/02-quick-reference.md

@@ -16,7 +16,7 @@ As themes grow more powerful, there's more to remember about how they work. We h
 [:notebook_with_decorative_cover: Theme Directory](/c/theme)
 [:jigsaw: Component Directory](/c/theme-component)
 [:wrench: Theme Modifiers](https://meta.discourse.org/t/theme-modifiers-a-brief-introduction/150605)
-[:wrench: Themeable site settings](PLACEHOLDER_THEMEABLE)
+[:wrench: Themeable site settings](https://meta.discourse.org/t/-/374376)
 
 ### File/Folder Structure <small>[read more](https://meta.discourse.org/t/structure-of-themes-and-theme-components/60848)</small>
 
@@ -118,7 +118,7 @@ html {
 }
 ```
 
-### Themeable site settings <small>[read more](PLACEHOLDER_THEMEABLE)</small>
+### Themeable site settings <small>[read more](https://meta.discourse.org/t/-/374376)</small>
 
 `about.json`:
 

docs/05-themes-components/09-theme-settings.md

@@ -6,7 +6,7 @@ id: theme-settings
 
 Discourse has the ability for themes to have "settings" that can be added by theme developers to allow site owners to customize themes through UI without having to change any line of code and worry about losing their changes with future updates for the theme.
 
-Themes can also alter certain themeable site settings, for more information on that, see the [Themeable site settings](PLACEHOLDER_THEMEABLE) topic.
+Themes can also alter certain themeable site settings, for more information on that, see the [Themeable site settings](https://meta.discourse.org/t/-/374376) topic.
 
 ## :heavy_plus_sign: Adding settings to your theme