fix rst quoting

docs/source/developer/extension_dev.rst

@@ -229,12 +229,12 @@ not enabled in our build configuration. To build a compatible package set
 Another option to try out your extension with a local version of JupyterLab is to add it to the
 list of locally installed packages and to have JupyterLab register your extension when it starts up.
 
-You can do this by adding your extension to the `jupyterlab.externalExtensions` key
- in the `dev_mode/package.json` file. It should be a mapping
-of extension name to version, just like in `dependencies`. Then run `jlpm run integrity`
-and these extensions should be added automatically to the `dependencies` and pulled in.
+You can do this by adding your extension to the ``jupyterlab.externalExtensions`` key
+ in the ``dev_mode/package.json`` file. It should be a mapping
+of extension name to version, just like in ``dependencies``. Then run ``jlpm run integrity``
+and these extensions should be added automatically to the ``dependencies`` and pulled in.
 
-When you then run `jlpm run build && jupyter lab --dev` or `jupyter lab --dev --watch` this extension
+When you then run ``jlpm run build && jupyter lab --dev`` or ``jupyter lab --dev --watch`` this extension
 will be loaded by default. For example, this is how you can add the Jupyter Widgets
 extensions: