Fix markdown syntax on hover (autozimu#1139)

Author: martskins

autoload/LanguageClient.vim

@@ -524,6 +524,8 @@ function! s:OpenHoverPreview(bufname, lines, filetype) abort
  endif
 
  call setline(1, lines)
+ " trigger refresh on plasticboy/vim-markdown
+ normal! i
  setlocal nomodified nomodifiable
 
  wincmd p