gfd stands for github flavored markdown

pandoc 2.11.1 has been used, issuing this series of commands:

- for f in *.mediawiki; do pandoc "$f" -f mediawiki -t gfm -o "${f%.mediawiki}.md"; done
- for f in *.md; do cp "$f" "${f%.md}.mediawiki"; done
- rm ???.md
- for f in *.mediawiki; do git mv "$f" "${f%.mediawiki}.md"; done