Fixed mismatched between doco contents and index
add empty docs
fix cons args in list example
add cons docs
add last docs
fixed the nth example
fixed subvec link
add hash docs
add is_empty docs
add partition_by docs
add into docs
fix partition_by example output
add concat docs
add flatten docs
add keys docs
add vals docs
add mapcat docs
add reduce_kv docs
clarify take_while and drop_while docs
add some docs