## Objective
- Makes `headless_renderer` example work instead of exiting without
effect.
- Guides users who actually just need
[`Screenshot`](https://docs.rs/bevy/0.16.1/bevy/render/view/window/screenshot/struct.Screenshot.html)
to use that instead.
This PR was inspired by my own efforts to do headless rendering, in
which the complexity of the `headless_renderer` example was a
distraction, and this comment from
https://github.com/bevyengine/bevy/issues/12478#issuecomment-2094925039
:
> The example added in https://github.com/bevyengine/bevy/pull/13006
would benefit from this change: be sure to clean it up when tackling
this work :)
That “cleanup” was not done, and I thought to do it, but it seems to me
that using `Screenshot` (in its current form) in the example would not
be correct, because — if I understand correctly — the example is trying
to, potentially, capture many *consecutive* frames, whereas `Screenshot`
by itself gives no means to capture multiple frames without gaps or
duplicates. But perhaps I am wrong (the code is complex and not clearly
documented), or perhaps that feature isn’t worth preserving. In that
case, let me know and I will revise this PR.
## Solution
- Added `exit_condition: bevy:🪟:ExitCondition::DontExit`
- Added a link to `Screenshot` in the crate documentation.
## Testing
- Ran the example and confirmed that it now writes an image file and
then exits.
1dfe83bb8d