Update cookbook/user_charges.ipynb

cookbook/user_charges.ipynb

@@ -76,7 +76,7 @@
     "tags": []
    },
    "source": [
-    "Components are usually by default loaded into OpenFE without pre-existing partial charges. This is particularly true when loading from [SDF and PDB files](?how do I reference another section?).\n",
+    "Components are usually by default loaded into OpenFE without pre-existing partial charges. This is particularly true when loading from [SDF and PDB files](https://docs.openfree.energy/en/stable/cookbook/loading_molecules.html).\n",
     "\n",
     "In those cases, partial charges will be assigned within the selected Protocol. As of writing, for `SmallMoleculeComponent`s this is done using [antechamber's](https://ambermd.org/antechamber/ac.html) `am1bcc` charge assignment, using the input conformer as the pre-optimized input for `sqm`'s AM1 calculation. For `ProteinComponent`s and `SolventComponent`s this is done by assigning charges from the chosen protein and solvent force fields.\n",
     "\n",