Broken link in class nav

In the left pane class nav for just about all pages (say, `https://docs.ruby-lang.org/en/master/ARGF.html`), the link `[HTTPRequestURITooLarge](https://docs.ruby-lang.org/en/master/Net/HTTPRequestURITooLong.html)` is broken.

(Plays havoc with the link checker:  shows up as 1200+ broken links.)