docs: give more context on the jupyter-boilerplate extension

Author: mariobuikhuizen

README.md

@@ -30,7 +30,9 @@ In JupyterLab, use the "Snippets" menu to select the snippet:
 
 ## Convert snippets from jupyter-boilerplate format
 
-See [jupyter-boilerplate-converter](jupyter-boilerplate-converter/README.md)
+See [jupyter-boilerplate-converter](jupyter-boilerplate-converter/README.md) on how to convert snippets from the
+[jupyter-boilerplate](https://github.com/moble/jupyter_boilerplate) classic notebook extension (not available for
+JupyterLab) to jupyterlab-snippets.
 
 ## Troubleshoot
 

jupyter-boilerplate-converter/README.md

@@ -1,7 +1,7 @@
 # jupyter-boilerplate-converter
 
-Convert snippets from the [jupyter-boilerplate](https://github.com/moble/jupyter_boilerplate)
-extension to [jupyterlab-snippets](../README.md).
+Convert snippets from the [jupyter-boilerplate](https://github.com/moble/jupyter_boilerplate) classic notebook
+extension (not available for JupyterLab) to [jupyterlab-snippets](../README.md).
 
 ## Usage