docs: fix typo

ktsn · web-flow · commit fd98c7b41d85 · 2020-02-11T00:26:42.000+08:00
diff --git a/docs/guide/extend-and-mixins.md b/docs/guide/extend-and-mixins.md
@@ -2,7 +2,7 @@
 
 ## Extend
 
-You can extend an existing class compnent as native class inheritance. Imagine you have following super class component:
+You can extend an existing class component as native class inheritance. Imagine you have following super class component:
 
 ```js
 // super.js
