R1:0771559d5815

Change "Contains Text" label to "Contains Words"

Summary: Fixes T4818. Clarify that this does not search for arbitrary text substrings.

Test Plan: `grep`

Reviewers: btrahan, chad

Reviewed By: chad

Subscribers: epriestley

Maniphest Tasks: T4818

Differential Revision: https://secure.phabricator.com/D9278