Document GLFW_FLOATING not supported on Wayland

include/GLFW/glfw3.h

@@ -4041,11 +4041,14 @@ GLFWAPI int glfwGetWindowAttrib(GLFWwindow* window, int attrib);
  *
  *  @errors Possible errors include @ref GLFW_NOT_INITIALIZED, @ref
  *  GLFW_INVALID_ENUM, @ref GLFW_INVALID_VALUE, @ref GLFW_PLATFORM_ERROR and @ref
- *  GLFW_FEATURE_UNAVAILABLE.
+ *  GLFW_FEATURE_UNAVAILABLE (see remarks).
  *
  *  @remark Calling @ref glfwGetWindowAttrib will always return the latest
  *  value, even if that value is ignored by the current mode of the window.
  *
+ *  @remark @wayland The [GLFW_FLOATING](@ref GLFW_FLOATING_attrib) window attribute is
+ *  not supported.  Setting this will emit @ref GLFW_FEATURE_UNAVAILABLE.
+ *
  *  @thread_safety This function must only be called from the main thread.
  *
  *  @sa @ref window_attribs