docs response: fix md list jank

docs/api/response.md

@@ -1,4 +1,3 @@
-
 # Response
 
   A Koa `Response` object is an abstraction on top of node's vanilla response object,
@@ -76,9 +75,9 @@
   - 510 "not extended"
   - 511 "network authentication required"
 
-  __NOTE__: don't worry too much about memorizing these strings,
-  if you have a typo an error will be thrown, displaying this list
-  so you can make a correction.
+__NOTE__: don't worry too much about memorizing these strings,
+if you have a typo an error will be thrown, displaying this list
+so you can make a correction.
 
 ### res.length=
 
@@ -243,4 +242,4 @@ this.response.lastModified = new Date();
 
 ```js
 this.response.etag = crypto.createHash('md5').update(this.body).digest('hex');
-```
+```