Issue on page 0.13 to 0.14

## Describe the issue

The code in the `onenter-state-schedules-now-run-before-startup-schedules` section appears to be incorrect. In `0.14 (Solution 2)`, `AppState::Setup` and `AppState::InitialSetup` are not defined in `enum AppState`. It's not clear what the intended solution is.

## Proposed Solution
Define those enum members if that's the intended solution. I'm not sure whether it is. Otherwise, change those states to something else, whatever the intended solution is.

Start with the `onenter-state-schedules-now-run-before-startup-schedules` section and inspect `0.14 (Solution 2)`, especially its use of `AppState::Setup` and `AppState::InitialSetup`. Compare those names with the `AppState` enum used by the example or relevant Bevy version. Done means the section presents valid state names and clearly reflects the intended solution.

Written by the indexing model from the issue text.