message: fix doc param name
diff: @@ -184,7 +184,7 @@ public:
  @param[in] collection_name Name of the collection used as a file name
  when saving
  - @param[in] bp_index_group Pointer to the blueprint index group in the
  + @param[in] bp_index_grp Pointer to the blueprint index group in the
  datastore, see the above schematic
  @param[in] domain_grp Pointer to the domain group in the datastore,
  see the above schematic
  