Update README.md

Author: jeylau

README.md

@@ -101,6 +101,8 @@ Suggested workflows, depending on the image folder contents:
 
     Saving works as described in *1*.
 
+    ***Note that if a new body part has been added to the `config.yaml` file after having started to label, loading the config in the GUI is necessary to update the dropdown menus and other metadata.***
+
 3. **Refining labels** – the image folder contains a `machinelabels-iter<#>.h5` file.
 
     The process is analog to *2*.