Fix feature typo

Author: janlazo

plug.vim

@@ -141,7 +141,7 @@ function! s:define_commands()
   endif
   if !has('nvim')
     \ && (has('win32') || has('win32unix'))
-    \ && (!has('multi-byte') || !has('iconv'))
+    \ && (!has('multi_byte') || !has('iconv'))
     return s:err('Vim needs +iconv, +multi_byte features on Windows to run shell commands.')
   endif
   command! -nargs=* -bar -bang -complete=customlist,s:names PlugInstall call s:install(<bang>0, [<f-args>])