Document WebP encoder limitations

[Shnatsel]

Explain the trade-offs involved and link to example code for encoding with libwebp.

[Shnatsel]

I see a lot of my PRs are approved but not merged. Does the project have a policy to require approval from several maintainers before merging a PR?

[HeroicKatora]

@Shnatsel CI hadn't finished when I pressed it (or Github didn't load). If you can, feel free to press the merge button on good judgment especially with approval there. Also

• clippy is broken again based on a long doc paragraph
• exr needs the latest version of miniz_oxide

Putting up this checklist just so I can communicate (including to myself) when I get around to fixing them.

[Shnatsel]

I do not have PR merge permissions on this repo.

[HeroicKatora]

Let's fix that as well, you'll want them in the coming months in any case I suppose.

[fintelia]

@Shnatsel I just added you to the 'Reviewers' team. That should give you write permissions to all the repositories under the image-rs org

[Shnatsel]

Thanks! I'll try not to make too much of a mess 😅

[fintelia]

Parts of this crate predate not just Rust 1.0, but crates.io itself. It'll always be at least somewhat messy 😄