Slack: Pipe REST API new tickets and commits to #core-rest-api channel

[netweb]

Slack: Pipe REST API new tickets and commits to #core-rest-api channel

If I'm reading this correctly from common/includes/slack/trac/config.php

	 * File paths that cause commits to be piped to particular channels.
	 * Start regex matches with # as your delimiter.

Then using rest-api as the file path in the patch should cover all of the following files and folders:

• src/wp-includes/rest-api.php
• src/wp-includes/rest-api
• tests/phpunit/tests/rest-api.php
• tests/phpunit/tests/rest-api
• tests/phpunit/includes/testcase-rest-api.php

[ocean90]

In 3066:

Slack: Send new tickets and commits for the "REST API" component to #core-restapi.

Props netweb.
Fixes #1332.