Hints in Contribution section

[terjanq]

Looks like hint boxes in Contribution section are broken.

[aaronshim]

This has been a problem since the v0.100 release of Hugo (I found it by bisecting known-good versions.) The likely cause is their attempted implementation of gohugoio/hugo#6703, which affects both markdownify and .Page.RenderString. The original authors of the book theme also ran into this problem at alex-shpak/hugo-book#452, which they solved with alex-shpak/hugo-book@6e1b44c.

This issue is also mentioned in #152.

My best attempt is to do a similar escape sequence as alex-shpak/hugo-book@6e1b44c (many other escape sequences, even safeHTML, do not work, as the final markdownify will attempt to render the {{< hint >}} shortcode regardless of what surrounds it), but it renders some of the extra escape sequences on the page, so we do have to do a bit of replace magic to get it back out.