markdown-include is GPL licensed.
Also, rewrite it as a block processor, so that it works correctly
inside indented blocks.
Signed-off-by: Anders Kaseorg <anders@zulip.com>
I have updated the docs for the SVN integration to properly indent the
code block etc as well as using 1. for the numbers rather than 1. 2. and
so on.
Fixes part of #17633.