title: NVim custom syntax highlighting does not work until I manually source init.vim
body: <p>I am having trouple understanding NVim / Vim custom syntax highlighting. I want to add highlighting for TODOs / FIXMEs and JavaDoc Tags (@param, @return, ...). The problem seems to be that either the regex syntax definitions or highlighting specifications do net get loaded until I source my init.vim again with a file opened.</p>
  <p>I already looked at <a href="https://stackoverflow.com/questions/4097259/in-vim-how-do-i-highlight-todo-and-fixme">this post</a> and added augroups but it did not help me with my problem. My current state after adding augroups looks like this:</p>
  <pre><code>augroup syntax_user_events
     autocmd!
     autocmd Syntax * syntax match todo /\v(TODO|NOTE|FIXME|OPTIMIZE|XXX)/ containedin=.*Comment
     autocmd Syntax * syntax match jdoc /\v(\@author|\@param|\@return|\@see)/ containedin=.*Comment
  augroup END
  
  augroup highlight_user_events
     autocmd!
     autocmd ColorScheme * highlight todo term=italic,bold cterm=italic ctermbg=darkyellow ctermfg=white gui=bold,italic guibg=darkyellow guifg=white
     autocmd ColorScheme * highlight jdoc term=bold cterm=bold ctermfg=white gui=bold guifg=white
  augroup END
  </code></pre>
  <p>I removed some of the JavaDoc Tags for better readability.</p>
  <p>Right now it does not highlight anything at all so I am questioning the augroup solution. The regex should work fine since it worked without augroups.</p>
  <p>I am not a Vim Pro at all, so if you need anything else like the Plugins I have or other settings, I am happy to provide them.</p>