Update docs/book/v4/overview.md

Author: alexmerlin

docs/book/v4/overview.md

@@ -12,7 +12,7 @@ It is more lightweight though, but supports controller plugins and event listene
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+[![GitHub license](https://img.shields.io/github/license/dotkernel/dot-controller)](https://github.com/dotkernel/dot-controller/blob/4.0/LICENSE.md)
 
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