tracking issue: examples

https://github.com/bevyengine/bevy-website/pull/225 introduced a new page for wasm examples at https://bevyengine.org/examples/

This page is currently lacking in style and not linked from the website. I think it should be the main page for example discovery instead of the git repo:
* it is easier to ensure that the examples are at the latest tag instead of main as the website is only about latest
* it is easier to evolve organisation with tags and categories instead of just a list of folders
* it is easier to control presentation as GitHub will always show files first, then the optional readme.md
* it is easier to have a nice presentation instead of just one large and basic readme.md

So... in case it's not clear, I think it would be easier.

What would be needed to get it in top shape:

- [x] add medatada to Cargo.toml about each example https://github.com/bevyengine/bevy/pull/4741
- display name
- description
- wasm enabled
- [ ] add an example page built with the dev docs
- [ ] update the website to display all examples with their metadata, but only build wasm version for the one where it is enabled
- WebGPU: https://github.com/bevyengine/bevy-website/pull/630
- WebGL2: https://github.com/bevyengine/bevy-website/pull/720
- non Wasm compatible: #1024
- [ ] remove/simplify the readme.md in bevy repo example folder. This file can't scale
- [x] link more prominently to the website for examples #335
- [x] (optional) add screenshot of the examples as part of the metadata https://github.com/bevyengine/bevy-website/pull/630
- [x] (optional) add tags to the metadata to help with discovery https://github.com/bevyengine/bevy-website/pull/742

This should be tied with https://github.com/bevyengine/bevy-website/issues/159 (bevy assets page) to evolve a consistent style.

The first two points need to be done before a release, the two next with that release

Start with the existing page at https://bevyengine.org/examples/ and the dev docs referenced in the issue, then trace how example metadata from Cargo.toml is exposed to the website. The work is done when the site presents all examples with their metadata, builds wasm only for wasm-enabled examples, and the remaining example README simplification is addressed.

Written by the indexing model from the issue text.