typo fix

There was a missing trailing underscore (`_`) that would have marked the
content in the backticks as a link. This adds it and fixes the link on
every core module page.

Modules are almost always written now by mutliple authors, so don't show this field on website, since it grows obsolete and does not take into account all contributors.
Contributors are still listed on github module source and in repo, and original authors still in the file for when development questions arise, but want
to funnel support questions to the mailing list versus directly to them.

Rename "jpfunc" to something more explanatory

tweak position & look of Requirements in rst
tweak APT's notes as per anhj's wish

return DOC and EXAMPLES as a list
add moduledev explanation
more

 Add HTML-escaping to code examples in rST tempate of module-formatter
 Add support for specifying port, addresses with phrases and attaching files
 Add support for custom headers and document version_added for new options
 X-Mailer header added :)
 protect empty address lists & attachment list, and add bcc

 - fixed template (it was the template), adding indentation with Jinja2
 - added description of code examples to man-page template (was missing)
 - fixed fireball, cron, and debug module examples to confrom

- notes is now supported
- multiline code examples are now supported (HTML rendering was off)

  - .rst now supresses default if none is set (looks better in HTML)
  - .rst now handles empty options list
  - Fixed postgresql_user and mysql_user because YAML contained colons
  - docs for facter

  plus a small fix in rst.j2 template
  manpages generated & checked
  modules.html generated & checked

Various tweaking to get the module formatter to work for 'make docs' in the docs project.  Likely the templates for other module formatting types will have to change
by the time I'm done.