Removed extra back tick. (#94)

README.md

@@ -143,7 +143,7 @@ c.setScissor(0, vec);
 Vulkan-Hpp generates references for pointers to structs. This conversion allows passing temporary structs to functions which can result in shorter code. In case the input is optional and thus accepting a null pointer the parameter type will be
 a ```vk::Optional<T> const&``` type. This type accepts either a reference to ```T``` or nullptr as input and thus allows optional temporary structs.
 
-````c++
+```c++
 // C
 ImageSubResource subResource;
 subResource.aspectMask = 0;