fix paths for include file resolution; set correct toc attributes

- set working directory and base directory so include files can be resolved
- enable toc using toc=preamble, clear toc2 attribute in both cases
- render method is deprecated, use convert instead
Merge branch 'render-fixes' of https://github.com/mojavelinux/asciidoc-preview into mojavelinux-render-fixes
Add include.adoc
Merge branch 'mojavelinux-render-fixes'