Migrate repo to use JVM toolchains Gradle feature.

^KT-46972 Fixed

ReadMe.md

@@ -41,20 +41,20 @@ Support for multiplatform programming is one of Kotlin’s key benefits. It redu
 
 ## Build environment requirements
 
-In order to build Kotlin distribution you need to have:
+This repository is using [Gradle toolchains](https://docs.gradle.org/current/userguide/toolchains.html) feature
+to select and auto-provision required JDKs from [AdoptOpenJdk](https://adoptopenjdk.net) project. 
 
-- JDK 1.6, 1.7, 1.8 and 9
-- Setup environment variables as following:
+Unfortunately [AdoptOpenJdk](https://adoptopenjdk.net) project does not provide required JDK 1.6 and 1.7 images,
+so you could either download them manually and provide path to installation via `JDK_16` and `JDK_17` environment variables or
+use following SDK managers:
+- [Asdf-vm](https://asdf-vm.com/)
+- [Jabba](https://github.com/shyiko/jabba)
+- [SDKMAN!](https://sdkman.io/)
 
-        JAVA_HOME="path to JDK 1.8"
-        JDK_16="path to JDK 1.6"
-        JDK_17="path to JDK 1.7"
-        JDK_18="path to JDK 1.8"
-        JDK_9="path to JDK 9"
-
-For local development, if you're not working on bytecode generation or the standard library, it's OK to have only JDK 1.8 and JDK 9 installed, and to point `JDK_16` and `JDK_17` environment variables to your JDK 1.8 installation.
-
-You also can use [Gradle properties](https://docs.gradle.org/current/userguide/build_environment.html#sec:gradle_configuration_properties) to setup `JDK_*` variables.
+Alternatively, it is still possible to only provide required JDKs via environment variables 
+(see [gradle.properties](./gradle.properties#L5) for supported variable names). To ensure Gradle uses only JDKs 
+from environmental variables - disable Gradle toolchain auto-detection by passing `-Porg.gradle.java.installations.auto-detect=false` option
+(or put it into `$GRADLE_USER_HOME/gradle.properties`).
 
 Note: The JDK 6 for MacOS is not available on Oracle's site. You can install it by