docs(jdk, macos): specify JDK11 or 14. JDK18 will not work

Author: mikehardy

docs/_getting-started-macos-android.md

@@ -28,7 +28,7 @@ brew install --cask zulu11
 
 The Zulu OpenJDK distribution offers JDKs for **both Intel and M1 Macs**. This will make sure your builds are faster on M1 Macs compared to using an Intel-based JDK.
 
-If you have already installed JDK on your system, make sure it is JDK 11 or newer.
+If you have already installed JDK on your system, make sure it is JDK 11 or JDK 14. JDK 18 is not supported yet.
 
 <h3>Android development environment</h3>