Set up automatic deployment

[mgrabovsky]

Set up a Travis script or a Jekyll environment to automatically generate static HTML from the Markdown documents and push it to the gh-pages branch after a push in master.

• Reverse engineer HTML template for Jekyll or Pandoc.
• Create a makefile with the appropriate instructions.
• Consider possible checking steps in build recipe. (Checking for dead links, for instance.)
• Add GitHub action for building the site on push.