[lint][spelling] delimeter -> delimiter

Summary:
I got bit by this one earlier (I swear I thought it was delimeter),
so I figured I would add it to the spelling data lint rule.

Test Plan:
changed an instance of delimiter to delimeter, ran `arc lint` fixed the
typo.

Reviewers: epriestley

Reviewed By: epriestley

CC: Korvin, aran

Differential Revision: https://secure.phabricator.com/D6936