R1:5794d45da31f

Fix word-break on remarkup tables

Summary: Tables headers break all kinds of funky even though we set `word-break` to word presumably because width is not calculated. Just use normal breaks.

Test Plan: Test developer documentation table in sand box, table is readable on desktop, phone break points.

Reviewers: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D14063