Indicate license badge to the license file self (#282)

Author: Goooler

README.md

@@ -2,7 +2,7 @@
 
 [![Kotlin Alpha](https://kotl.in/badges/alpha.svg)](https://kotlinlang.org/docs/components-stability.html)
 [![JetBrains incubator project](https://jb.gg/badges/incubator.svg)](https://confluence.jetbrains.com/display/ALL/JetBrains+on+GitHub)
-[![GitHub license](https://img.shields.io/badge/license-Apache%20License%202.0-blue.svg?style=flat)](http://www.apache.org/licenses/LICENSE-2.0)
+[![GitHub license](https://img.shields.io/github/license/kotlin/kotlinx-io)](LICENSE)
 [![Download](https://img.shields.io/maven-central/v/org.jetbrains.kotlinx/kotlinx-io-core)](https://central.sonatype.com/artifact/org.jetbrains.kotlinx/kotlinx-io-core/)
 [![Kotlin](https://img.shields.io/badge/kotlin-1.9.22-blue.svg?logo=kotlin)](http://kotlinlang.org)
 [![TeamCity build](https://img.shields.io/teamcity/build/s/KotlinTools_KotlinxIo_BuildAggregated.svg?server=http%3A%2F%2Fteamcity.jetbrains.com)](https://teamcity.jetbrains.com/viewType.html?buildTypeId=KotlinTools_KotlinxIo_BuildAggregated&guest=1)