Fix typo in repository plugin example (#487)

source/plugins/repositories/README.md

@@ -22,5 +22,5 @@ Because of limitations of using SVG inside of `<img>` tags, people won't be able
   with:
     # ... other options
     plugin_repositories: yes
-    plugin_repositories_list: lowlighter/metrics, denoland/deno  # List of repositories you want to feature
-```
+    plugin_repositories_featured: lowlighter/metrics, denoland/deno  # List of repositories you want to feature
+```