Health: rework syntax (#5744)

- By re-enabling code blocks (every line that doesn't begin with a "-" and is
  indented by at least 4 spaces), we prevent the Markdown syntax to evaluate "_"
  as beginning for italic text.

  That's the case for `:CheckHealth deoplete` for instance. It would output:

    $ cat /tmp/log_{PID}

  Since the deoplete check gets run first, almost all of the following
  `:CheckHealth` output would be italic.

- Since we re-enable code blocks, we now have to tell our custom syntax that it
  can be part of markdownCodeBlock as well. Otherwise there would be no
  highlithing for our keywords ERROR, INFO, etc. after 4 spaces of indent.

- Since we do the above anyway, we make it work for mkdListItemLine as well.
  That's a highlight group from `plasticboy/vim-markdown` opposed to the shipped
  markdown syntax (which essentially is `tpope/vim-markdown`). Before this patch
  there was no highlighting at all in the `:CheckHealth` output.

0 files changed, 0 insertions, 0 deletions