Add note about JDK_16 in readme
diff --git a/README.md b/README.md
index 8cc87c8..4b15fd1 100644
--- a/README.md
+++ b/README.md
@@ -161,7 +161,7 @@
 ### Requirements
 
 * JDK >= 1.8 referred to by the `JAVA_HOME` environment variable.
-* JDK 1.6 referred to by the `JDK_16` environment variable.
+* JDK 1.6 referred to by the `JDK_16` environment variable. It is okay to have `JDK_16` pointing to `JAVA_HOME` for external contributions.
 
 ## Contributions and releases