Hover through the documentation in CoC

init.vim

" Use K to show documentation in preview window.
" For most purposes (mostly class), it's better to keep the call to man
au Filetype rust,java,go nnoremap <silent> K :call <SID>show_documentation()<CR>
"nnoremap <silent> K :call <SID>show_documentation()<CR>

function! s:show_documentation()
  if (index(['vim','help'], &filetype) >= 0)
    execute 'h '.expand('<cword>')
  else
    call CocAction('doHover')
  endif
endfunction

" Because everyone deserves a chance to scroll through long documentation:
" ^K jumps into the floating window
" A second ^K closes the floating window and returns to the orignal buffer
" If no floating window exists when the first ^K is pressed, open the floating window 
nnoremap <silent> <expr> <C-k> ( coc#float#has_float() ?
    \    (exists('w:float') ? 
    \        ":call coc#float#close_all()<CR>" :
    \        ":call coc#float#jump()<CR>") : 
    \    ":call <SID>show_documentation()<CR>")