Typo

Author: yuphin

README.md

@@ -56,7 +56,7 @@ Currently, Lumen only builds on Windows, however, there is no platform specific
 Some of the sample scenes can be found in the `scenes/` directory.
 Sample scene files with various integrators can be found in the `scenes/cornell_box/` directory.
 
-To load the scene file simply run
+To load a scene file simply run:
 ```shell
 Lumen.exe <scene_file>
 ```