docs: overhaul TOON example

Author: johannschopplich

README.md

@@ -76,7 +76,8 @@ AI is becoming cheaper and more accessible, but larger context windows allow for
 }
 ```
 
-YAML conveys the same information with **fewer tokens**:
+<details>
+<summary>YAML conveys the same information with <strong>fewer tokens</strong></summary>
 
 ```yaml
 context:
@@ -110,6 +111,8 @@ hikes:
     wasSunny: true
 ```
 
+</details>
+
 TOON conveys the same information with **even fewer tokens**, while keeping the hikes in a clear tabular layout:
 
 ```toon