Update molecule.rst

doc/src/molecule.rst

@@ -201,11 +201,9 @@ bonds between nuclear cores and Drude electrons in a different manner.
 
 Each section is listed below in alphabetic order.  The format of each
 section is described including the number of lines it must contain and
-rules (if any) for whether it can appear in the data file.  In each
-case the ID is ignored; it is simply included for readability, and
-should be a number from 1 to Nlines for the section, indicating which
-atom (or bond, etc) the entry applies to.  The lines are assumed to be
-listed in order from 1 to Nlines, but LAMMPS does not check for this.
+rules (if any) for whether it can appear in the data file.  For per-
+atom sections, entries should be numbered from 1 to Natoms, where
+Natoms is the number of atoms in the template.
 
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