Document non-goals of Gitify

[bmulholland]

What things won't we do, and why? Let's write them down.

I'll start by collecting them here. We can add to the README later.

• Operating-system level features
  • Do not disturb, including on schedules. Request: show notifications only for certain time periods #416 (comment)
  • Persistent notifications like persistent pop-up notifications #281. e.g. macOS has Alerts, instead of Banners, which make them persistent
• Seeing past notifications. This is a tool for monitoring new notifications, not seeing old ones, which can be seen at https://github.com/notifications.
• Specific UX/UI changes that add options and/or visual complexity for minor workflow improvements. e.g. UI enhancement: when you get one notification and currently have none #358 and Feature Request: Open all notifications at once #411
• UI for something that isn't core to Gitify, and/or can be trivially done another way. e.g. Feature request: To provide a button to go to logged in user profile directly #476 and Add link to watching on GitHub #221
• Support anything other than Github. Doing so would be a major undertaking that we maaayyy consider in future, but it would be a ton of work and there's so much tied to Github right now that it's not something I'd want to maintain.