hdf5doc

Description:
    Changed H5LTfind_dataset and h5ltfind_dataset_f entries to describe 
        current actual behavior (loc_id must be a group identifier;
        dset_name must a dataset within that group).
    -- Bugzilla 1596: Temporarily fixes the documentation portion,
        but does not close the bug; RM entry will revised again if function 
        is changed to be more flexible.
    Copy edits and other edits for clarity.