Implement hot reloading

README

@@ -13,4 +13,16 @@ The build is handled with CMake (version 3.10 or later):
 The path to a directory containing the assets must be passed on the
 command line to run the game:
 
-   build/app/game ASSETS-DIR
+   build/game/game ASSETS-DIR
+
+
+							Hot Reloading
+
+The engine supports hot reloading of the game code via the F5 key; set
+the HOTRELOAD option on in CMake to enable it. You also have to run an
+executable built from the engine rather than the game if using this
+feature.
+
+	cmake -B build -D HOTRELOAD=ON
+	cmake --build build
+	build/engine/engine assets/