Added clearer ZIP download instructions to readme

README.md

@@ -8,6 +8,7 @@ Usage
 -----
 * Install Blender 2.76 or greater: http://blender.org/download/
 * Download newest `add_mesh_SpaceshipGenerator.zip` from the  [Releases](https://github.com/a1studmuffin/SpaceshipGenerator/releases) section
+* NOTE: If your downloaded ZIP is called `SpaceshipGenerator-master.zip` you have downloaded the wrong thing, see above
 * Under File > User Preferences... > Add-ons > Install From File... open the downloaded ZIP file
 * Under File > User Preferences... > Add-ons enable this script (search for "spaceship")
 * Add a spaceship in the 3D View under Add > Mesh > Spaceship