aider: Add the redirect plugin to the _config.yml.

# Aider chat conversation:

USER: add the redirect plugin

ASSISTANT: To add the Jekyll Redirect From plugin to your `_config.yml`, you need to add the plugin to the `plugins` list. Here's the diff for the change:

```diff
--- _config.yml
+++ _config.yml
@@ ... @@
 theme: jekyll-theme-cayman
 url: "https://aider.chat"
+plugins:
+  - jekyll-redirect-from
+
 defaults:
   - scope:
       path: "README.md"
       type: "pages"
     values:
       description: "A command-line chat tool for coding with GPT"
```

_config.yml

@@ -1,6 +1,9 @@
 theme: jekyll-theme-cayman
 url: "https://aider.chat"
 
+plugins:
+  - jekyll-redirect-from
+
 defaults:
   - scope:
       path: "README.md"