Update Status and Roadmap section on About page

[jnny]

Last updated July 2023, so long overdue: https://ouisync.net/about/

Current text reads:

July 2023: We are soft launching the first stable release of Ouisync this month! Please note that the app is under active development, and as such some features and functionality may not work as expected. We encourage users to report bugs and request new features via Github

Upcoming Milestones:

Ouisync on iOS
Security Audit
Ouisync SDK