Add homebrew to /integrations

[mikermcneil]

https://fleetdm.com/integrations

wording: "Deploy software with Fleet and homebrew."

type of integration: package registry

FUTURE: add autopkg, installamator, chocolatey, and munki too as we make these pluggable

[fleet-release]

Homebrew integration,
Fleet and software in sync,
Ease in each action.

[fleet-release]

Homebrew joins the fleet,
Software flows like clear spring creek,
Ease in each deploy.