Replace broken link with @see annotation to text representation of the linked image

Source/inv.cpp

@@ -49,7 +49,6 @@ bool drawsbarflag;
  *              55 56 57 58 59 60 61 62 63 64
  *
  * 65 66 67 68 69 70 71 72
- * @see graphics/inv/inventory.png
  */
 const Point InvRect[] = {
 	// clang-format off

Source/inv.h

@@ -35,8 +35,10 @@ enum inv_item : int8_t {
 	// clang-format on
 };
 
-// identifiers for each of the inventory squares
-// see https://github.com/sanctuary/graphics/blob/master/inventory.png
+/**
+ * identifiers for each of the inventory squares
+ * @see #InvRect
+ */
 enum inv_xy_slot : uint8_t {
 	// clang-format off
 	SLOTXY_HEAD_FIRST       = 0,