title: Vim polyglot syntax highlighting not overriding default
body: <p>I have made sure that <code>syntax on</code> was enabled, and I can see vim going from all-grey (no highlighting), to a colored version where there is some basic syntax highlighting going on. So default syntax highlighting works.</p>
  
  <p>Afterwards, I have installed the <code>https://github.com/sheerun/vim-polyglot</code> plugin to my vim editor. The contents of my <code>~/.vimrc</code> file read this way:</p>
  
  <pre><code>...
  
  if has("syntax")
    syntax on
  endif
  
  ...
  
  call plug#begin('~/.vim/plugged')
  
  Plug 'https://github.com/preservim/nerdtree.git'
  Plug 'https://github.com/sheerun/vim-polyglot.git'
  
  call plug#end()
  ...
  </code></pre>
  
  <p>After this, I didn't see any change. I still see this very basic syntax highlighting but nothing any different to what I had before. How to make polyglot override this very basic syntax highlighting?</p>