Include brand guidelines
You'll notice that a big chunk of Slack's media landing page is occupied by their brand guidelines. This is a sensible thing to include if your business has reached a certain magnitude – after all, you want to make sure your brand is represented accurately and consistently.
Brand guidelines include things like the number of pixels people should leave clear around your logo when using it, and the typeface or colors they should use when representing your brand.
These nitty-gritty details may seem like overkill, but they're important to define in certain contexts – for example, if an external party is building some creative for you, such as a feature in their print publication or an entry in a pamphlet on their event lineup.
For smaller businesses and those not looking to have creative made externally, it's ok to skip the guidelines for the time being.