Update README.md

Fixed broken VM file link

Author: brittjay0104

artifact_documentation/README.md

@@ -21,7 +21,7 @@ All the above listed artifacts, with the exception of the virtual machine file,
 *Copied from INSTALL.md*
 
 1. Download [VirtualBox](https://www.virtualbox.org).
-2. Download virtual machine file [CausalTesting_Artifact.ova](https://drive.google.com/open?id=1hyzHYCQEkOzYiLGldkBVxNvQt0Phb-th).
+2. Download virtual machine file [CausalTesting_Artifact.ova](https://gmuedu-my.sharepoint.com/:u:/g/personal/johnsonb_gmu_edu/EXtV-gff48tHszUt9A55nYQBu0YIVe9SW5DDB4jBXLM8VA?e=bWzSac).
 <br> **Please note this is a large file (5BG) and may take some time to download.**
 3. Open VirtualBox.
 4. Go to **File > Import Appliance...**