docs on complexes + periodic image

docs/source/content/defining-defects.ipynb

@@ -169,7 +169,8 @@
     "- One where the two parts of the defect complex are nearest neighbors (`def_comp0`).\n",
     "- One where the two defects are next-nearest neighbors (`def_comp2`).\n",
     "\n",
-    "Since our defect complex definition accounts for an effective _Center of Mass_ site, we can properly account for periodic boundary conditions. the two defect complexes will be considered not equal."
+    "Since our defect complex definition accounts for an effective _Center of Mass_ site, we can properly account for periodic boundary conditions. the two defect complexes will be considered not equal.\n",
+    "For complexes, we recommend checking the structure with the center of mass (`defect_structure_with_com`) to make sure you understand exactly what will be simulated in the supercell."
    ]
   },
   {