Documentation: Fix link (#860)

Author: runephilosof-abtion

RUNNING_UNIT_TESTS.md

@@ -5,7 +5,7 @@ This process is much easier than it has been before!
 
 ## MS SQL SERVER
 
-If you don't have easy access to MS SQL Server, you can set up a Vagrant/VirtualBox virtual machine with MS SQL Server. [Here's how](/https://github.com/rails-sqlserver/activerecord-sqlserver-adapter-dev-box).
+If you don't have easy access to MS SQL Server, you can set up a Vagrant/VirtualBox virtual machine with MS SQL Server. [Here's how](https://github.com/rails-sqlserver/activerecord-sqlserver-adapter-dev-box).
 
 ## TL;DR