Minor doc update

loop/doc/structure_db.rst

@@ -508,7 +508,7 @@ This example illustrates how to create a custom FragDB based on a StructureDB:
     :param c_stem: The C-stem
     :type c_stem:  :class:`ost.mol.ResidueHandle`
     :param frag_size: Number of residues of the fragment
-    :type frag_size:  :class:`float`
+    :type frag_size:  :class:`int`
     :param extra_bins: Whether to extend the search to include fragments from
                        *extra_bins* additional bins surrounding the bin given by
                        the *n_stem* and *c_stem* geometry. If odd, we extend to