update README JLab version compatibility

DenisaCG · DenisaCG · commit 76270439503e · 2024-08-16T13:44:02.000+02:00
diff --git a/README.md b/README.md
@@ -16,7 +16,7 @@ Repo: https://github.com/google/blockly
 
 ## Requirements
 
-- JupyterLab >= 4.0.0
+- JupyterLab >= 4.0.0 (older versions available for 3.6)
 
 ## Install
 
