Fix typo about table settings in server.en.yml
Fix typo about table settings in server.en.yml

Intrepid n00b pull request at encouragement by @zogstrip. Fixing a small typo, as discussed on meta: https://meta.discourse.org/t/typo-in-description-of-allow-html-tables-admin-setting/32835?u=tobiaseigen
natefinch/discourse,natefinch/discourse