[BUGFIX] Add some more information on the build requirements

CMakeLists.txt

@@ -111,6 +111,7 @@ set(ANKI_GR_BACKEND "GL" CACHE STRING "The graphics API (GL or VULKAN)")
 if(${ANKI_GR_BACKEND} STREQUAL "GL")
 	set(GL TRUE)
 	set(VULKAN FALSE)
+	set(VIDEO_VULKAN TRUE) # Set for the SDL2 to pick up
 else()
 	set(GL FALSE)
 	set(VULKAN TRUE)

README.md

@@ -35,6 +35,7 @@ Prerequisites:
 - Cmake 2.8 and up
 - GCC 5.0 and up or Clang 3.7 and up
 - libx11-dev installed
+- libxrandr-dev installed
 - [Optional] libxinerama-dev if you want proper multi-monitor support
 
 To build the release version: