Fix in a typo in an HTML entity.

I noticed a typo in a HTML entity shown when you try to check your existing grades. This revision should (hopefully) fix the typo, and avoid showing markup to users. See the diff under 'Files Changed'.  This should be a one-line change to a single file, if I did this right.

(My earlier pull request from an hour ago should be ignored/disregarded -- if you can't see it, perfect!)