Add info about compiler versions to README

Author: tschuchortdev

README.md

@@ -102,6 +102,16 @@ dependencies {
 
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+## Compatible Compiler Versions
+
+Kotlin-Compile-Testing is compatible with all _local_ compiler versions. It does not matter what compiler you use to compile your project. 
+
+However, if your project or any of its dependencies depend directly on compiler artifacts such as `kotlin-compiler-embeddable` or `kotlin-annotation-processing-embeddable` then they have to be the same version as the one used by Kotlin-Compile-Testing or there will be a transitive dependency conflict.
+
+- Current `kotlin-compiler-embeddable` version: `1.3.60`
+
+Because the internal APIs of the Kotlin compiler often change between versions, we can only support one `kotlin-compiler-embeddable` version at a time. 
+
 ## License
 
 Copyright (C) 2019 Thilo Schuchort