Convert Didigm spec to Markdown.

--HG--
rename : didigm/doc/didigm.html => didigm/didigm.markdown
Pretty much by definition, this repo only contains docs anyway.

--HG--
rename : madison/doc/Madison.falderal => madison/Madison.markdown
rename : mdpn/doc/mdpn.html => mdpn/mdpn.markdown
rename : oozlybub-and-murphy/doc/oozlybub-and-murphy.html => oozlybub-and-murphy/oozlybub-and-murphy.markdown
rename : opus-2/doc/opus-2.html => opus-2/opus-2.markdown
rename : sartre/doc/sartre.markdown => sartre/sartre.markdown
rename : star-w/doc/star-w.markdown => star-w/star-w.markdown
rename : tamerlane/doc/tamerlane.html => tamerlane/tamerlane.markdown
rename : turkey-bomb/doc/turkey-bomb.markdown => turkey-bomb/turkey-bomb.markdown
rename : urreading/doc/urreading.html => you-are-reading-the-name-of-this-esolang/you-are-reading-the-name-of-this-esolang.markdown
Convert HTML to Markdown (thanks, pandoc!)