If you have an old version of "Source Code Pro" on your computer, it will WRECK that page in a lot of fun and interesting ways.
You can either remove "Source Code Pro" from your box, or use Tampermonkey / Greasemonkey to remove it from the markup.
People were hitting that a few months ago, is this the first time that you've visited the docs in a while? In their case it was due to a problem with the page's font file itself, and it may be that your browser still has that version of the font cached. Maybe try a force-refresh?
Hmmm. Force refresh did nothing. It's possible I have Source Code Pro like the other commenter suggests. Dunno