[Docs] Fix links in main README (#1651)

docs/README.md

@@ -17,7 +17,7 @@ better yet, a pull request.
       - [Create an App](getting-started/create-an-app.md)
       - App configuration
         - [Configuring App with plugins](getting-started/configure-app-with-plugins.md)
-        - [Customize the look-and-feel of your App](getting-started/customize-app-look-and-feel.md)
+        - [Customize the look-and-feel of your App](getting-started/app-custom-theme.md)
       - Deployment scenarios
         - [Kubernetes](getting-started/deployment-k8s.md)
         - [Other](getting-started/deployment-other.md)
@@ -67,7 +67,7 @@ better yet, a pull request.
     - [Glossary](auth/glossary.md)
   - Designing for Backstage
     - [Backstage Design Language System (DLS)](dls/design.md)
-    - [Storybook -- reusable UI components](dls/storybook.md)
+    - [Storybook -- reusable UI components](http://storybook.backstage.io)
     - [Contributing to Storybook](dls/contributing-to-storybook.md)
     - [Figma resources](dls/figma.md)
   - API references

docs/features/software-catalog/index.md

@@ -21,4 +21,6 @@ can be organised around the entities in the catalog.
 
 ## Using the Service Catalog
 
+TODO
+
 ![](service-catalog-home.png)