add JEP 42 (voila incorporation) to readme

Author: Zsailer

README.md

@@ -26,6 +26,7 @@ Below is a list of JEPs that have been submitted. To view the discussion around
 | 0026 | **Submitted** | [Add Language Server Support to Jupyter Server and jupyterlab-monaco](https://github.com/jupyter/enhancement-proposals/pull/26) |
 | 0028 | **Submitted** | [Standalone Jupyter Server](https://github.com/jupyter/enhancement-proposals/pull/28) |
 | 0029 | **Submitted** | [Jupyter Enhancement Proposal updates](https://github.com/jupyter/enhancement-proposals/pull/29)
+| 0042 | **Accepted** | [Voila Incorporation](https://github.com/jupyter/enhancement-proposals/pull/42)
 
 ## How do I submit a JEP?