Set theme jekyll-theme-cayman

This re-enables navigation through website.

Start using `details` HTML tag to condense content

From this point forward, assets that are used for maintaining this re…

…pository (images, scripts, etc.) will be added alongside the rest of the content for easier maintenance.

Add notes section

Add GreetBot and improve Slack integrations

Add Slack integrations

Add TeX rendering, drop support for GitHub Pages

TeXify is a GitHub app that renders TeX expressions in README files.
However, I haven't found a way to make it work nicely with a website
hosted on GitHub Pages. Relative links are also handled a bit
differently with GitHub Pages, which sometimes causes issues. For
those reasons, I am now dropping support of the REPL as a website in
favor of simple GitHub README files directly accessible on GitHub.
Because mathematics are key to our understanding, I am favoring
TeXify over the looks of a better design. If a solution comes up,
I will gladly re-add support for GitHub Pages.

Add kinks section

Enabling GitHub Pages