correct typo in compounds list column headers

Former-commit-id: 2d4a7a942f8bb8da801cb652f43a3e50f567111a

ippisite/ippidb/templates/compound_t_list.html

@@ -15,7 +15,7 @@
       {% include "compound_t_colhead.html" with col_id="nb_rotatable_bonds" col_name="number of rotatable bonds" %}
       {% include "compound_t_colhead.html" with col_id="nb_aromatic_sssr" col_name="number of aromatic SSSR" %}
       {% include "compound_t_colhead.html" with col_id="families" col_name="PPI families" %}
-      {% include "compound_t_colhead.html" with col_id="nb_chiral_centers" col_name="Number of chiral centerrs" %}
+      {% include "compound_t_colhead.html" with col_id="nb_chiral_centers" col_name="Number of chiral centers" %}
       <button type="button" class="btn btn-primary float-right" style="width: inherit!important" data-toggle="modal" data-target="#selectColumns">
         <i class="fa fa-columns" title="customize columns"></i>
       </button>