adding installer for Revit 2018 / 2018.1

Author: daren-thomas

README.md

@@ -22,6 +22,7 @@ writing your Revit Addins - use this in combination with the [RevitLookup](https
 
 ## Installation
 
+- [Installer for Autodesk Revit 2018 (and 2018.1)](https://github.com/architecture-building-systems/revitpythonshell/releases/download/2017.07.24/2017.07.24_Setup_RevitPythonShell_2018.exe)
 - [Installer for Autodesk Revit 2017](https://github.com/architecture-building-systems/revitpythonshell/releases/download/2017.04.06/2017.04.06_Setup_RevitPythonShell_2017.exe)
 - [Installer for Autodesk Revit 2016](https://github.com/architecture-building-systems/revitpythonshell/releases/download/2017.03.07/2017.03.07_Setup_RevitPythonShell_2016.exe)
 - [Installer for Autodesk Revit 2015](https://github.com/architecture-building-systems/revitpythonshell/releases/download/2017.03.07/2017.03.07_Setup_RevitPythonShell_2015.exe)