correct error message text, sync with source

<dt><em>Bad TIP4P bond type for PPPMDisp/TIP4P</em></dt>

<dd>Specified bond type is not valid.</dd>

<dt><em>Bad fix ID in fix append/atoms command</em></dt>

<dd>The value of the fix_id for keyword spatial must start with the suffix

<a href="#id6"><span class="problematic" id="id7">f_</span></a>.</dd>

<dd>The value of the fix_id for keyword spatial must start with &#8216;<a href="#id6"><span class="problematic" id="id7">f_</span></a>&#8216;.</dd>

<dt><em>Bad grid of processors</em></dt>

<dd>The 3d grid of processors defined by the processors command does not

match the number of processors LAMMPS is being run on.</dd>

{Bad fix ID in fix append/atoms command} :dt

The value of the fix_id for keyword spatial must start with the suffix

f_. :dd

The value of the fix_id for keyword spatial must start with 'f_'. :dd

{Bad grid of processors} :dt