finalise interface & documentation

Signed-off-by: Folling <mail@folling.io>

include/ikarus/global.h

@@ -0,0 +1,16 @@
+#pragma once
+
+/// \file memory.h
+/// \author Folling <folling@ikarus.world>
+
+#include <ikarus/macros.h>
+
+/// \addtogroup global Global
+/// \brief Information relevant to the entire library.
+/// @{
+
+/// \brief Frees a pointer allocated by ikarus. Every pointer returned by a function must be freed using this function unless
+/// explicitly stated otherwise.
+IKA_API void ikarus_free(void * ptr);
+
+/// @}