Just a few links:
- Where everything is documented: http://pandoc.org/MANUAL.html
- If you have questions or suggestions: https://groups.google.com/forum/#!forum/pandoc-discuss
- Contributing to pandoc is also a great way to get your feet wet with Haskell. In my experience, very supportive community. See http://pandoc.org/CONTRIBUTING.html and for good first issues: https://github.com/jgm/pandoc/issues?q=is%3Aopen+is%3Aissue+...
Finally, a great feature, that hasn't been mentioned here, is pandoc filters. Basically, pandoc provides a way for scripts (in any programming language) to hook into the transformation pipeline and modify the document AST (similar to the HTML DOM) in-between the reading and writing steps. See http://pandoc.org/filters.html