Improve examples order - 2D Rendering

**What problem does this solve or what need does it fill?**

Currently the book points the user to continue learning how to use Bevy by checking the examples, but the examples have no clear order.

**Describe the solution would you like?**

In 2D Rendering you have:

- contributors
- sprite_sheet
- sprite
- texture_atlas

Where contributors uses a lot more features than sprite.

In my opinion it would be much nicer to have:
- sprite
- sprite_sheet
- texture_atlas
- Add something that would use the result of the texture atlas
- contributors

The idea would be that the 2D rendering would read almost like a book, where first you learn to render a single sprite, then a whole animation using a sprite sheet, then how to make a texture atlas and finally how to use that atlas to make something more complex.

I haven't checked the other chapters, but if they are similar, it would be nice to also structure them in a logical/progressive way. I hope this issue can open a discussion for other chapters to, maybe in separate issues.

If you want me to, I can make a first PR to reorder said examples (I will not add something that would use the result of the texture atlas, as I am still learning the how to use this).

**Describe the alternative(s) you've considered?**

NaN

**Additional context**

My idea behind this would be that once a topic like this has examples presented in a progressive order, these can then be used to write chapters for the book.

Start by locating the 2D Rendering examples and the book material that directs readers to them, then compare their current order with the proposed progression from sprite to contributors. Done means the examples teach the concepts in a clear sequence, with any decision about adding a texture-atlas example documented before implementation.

Written by the indexing model from the issue text.