Explicitly use Magnum::Math::Literals namespace.

doc/generated/hello.cpp

@@ -31,6 +31,7 @@
 #include <Magnum/Platform/Sdl2Application.h>
 
 using namespace Magnum;
+using namespace Magnum::Math::Literals;
 
 class Hello: public Platform::Application {
 public:

doc/generated/shaders.cpp

@@ -67,6 +67,7 @@
 #include "configure.h"
 
 using namespace Magnum;
+using namespace Magnum::Math::Literals;
 
 struct ShaderVisualizer: Platform::WindowlessApplication {
     using Platform::WindowlessApplication::WindowlessApplication;