include versionadded tag

src/library.cpp

@@ -756,6 +756,8 @@ double lammps_get_thermo(void *handle, const char *keyword)
  *
 \verbatim embed:rst
 
+.. versionadded:: TBD
+
 This function provides access to cached data from the last thermo output.
 This differs from :cpp:func:`lammps_get_thermo` in that it does not trigger
 an evaluation.  Instead it provides direct access to a read-only location