update rustdoc to readme

[mirsella]

https://vladbat00.github.io/bevy_egui_web_showcase/index.html gives a 404

[vladbat00]

Hm, I can't reproduce it. I changed my nickname not so long ago, the previous link was https://mvlabat.github.io/bevy_egui_web_showcase/index.html, which is now 404. Where I forgot to update the link though is https://github.com/vladbat00/bevy_egui/blob/581a0e1b423e3fae4d3a011c08c8d8000702b544/src/lib.rs. And it's not the only inconsistency with the current readme file... Maybe you were checking the link from docs.rs (which reads the contents from src/lib.rs)?

[mirsella]

ohhh yes thats it

[vladbat00]

Fixed in #333, thanks