chore: fix spelling (#304)

Author: robis24

Diff for: README.md

@@ -1,7 +1,7 @@
 # Vue Vapor
 
 > [!IMPORTANT]
-> We're currently building Vapor on [core's vapor branch](https://github.com/vuejs/core/tree/vapor), this repo wasn't maintained now.
+> We're currently building Vapor on [core's vapor branch](https://github.com/vuejs/core/tree/vapor), this repo isn't maintained now.
 
 
 This repository is a fork of [vuejs/core](https://github.com/vuejs/core) and is used for research and development of no virtual dom mode.