condense readme

README.md

@@ -597,8 +597,8 @@ log.child({ widget: 'foo' }).info('hello')
 log.child({ widget: 'bar' }).warn('hello 2')
 ```
 
-<a name="extreme"></a>
-## Extreme mode explained
+<details>
+<summary>## Extreme mode explained<a name="extreme"></a></summary>
 
 In essence, Extreme mode enables extreme performance by buffering log messages and writing them in larger chunks.
 
@@ -625,7 +625,7 @@ This has a couple of important caveats:
   ```
 
 So in summary, only use extreme mode if you're doing an extreme amount of logging, and you're happy in some scenarios to lose the most recent logs.
-
+</details>
 
 <a name="express"></a>
 ## How to use Pino with Express