Fix typos (pt)
Restore old news post

Fix old post with links to conference material:

* restore links in 'ja' version by adopting the external links from 'en'
* fix broken markdown and content in 'en', 'de', and 'ko' versions
  (which have already been broken on the Radiant CMS site);
  missing content and links were taken from an archived page
Fix links in old news post
Translate latest news (pl)
Merge branch 'fix-links'
Fix broken link markdown in old news post