Design/API doc: Clarify what will be released and working

[dbish]

Notes from today's meeting on this, the MVP will be a Rust create + an example w/ a small tauri app.

Functionality:

1. Mac and Windows app streaming/capture, to a local file.
2. Able to toggle to capture the whole screen as an option
3. Able to list windows to capture
4. Able to choose which window to capture from list
5. Able to stop capturing individual windows

Example that will be shipped with it:

1. Small tauri app for front end
2. Window picker to pick a window
3. Window is shared with GPT (user has to enter their own key in the code/config)
4. Able to ask questions based on windows by sending to GPT4-V

Post-MVP will include:

1. Audio + camera