Update README

[randomPoison]

Update the README to better reflect the current state of the project and provide more information to users:

• Remove note about the project being experimental now that we're largely production-ready.
• Add a section with build instructions, noting the additional dependency on nasm.
• Flesh out the section on testing to note the need to install meson, recommend the opt-dev profile, and document the extra args for test.sh.
• Add usage instructions, mostly just documenting that we expose the same C API as dav1d.

Let me know if there's any other information I should add to the README.

[kkysen]

Could you wrap lines? The long lines are fine when rendered in Markdown, but they're annoying to comment on and diff. Line breaks at end of sentences or phrases would be good I think.

Also, can you mention the features that you can build with? So how to build without asm support, or build for only one bitdepth. That's different from dav1d so it seems appropriate here.

[randomPoison]

Could you wrap lines? The long lines are fine when rendered in Markdown, but they're annoying to comment on and diff. Line breaks at end of sentences or phrases would be good I think.

I've wrapped the lines at 80 characters wide. I'd prefer to do it that way over semantic wrapping because I can use a tool to update wrapping automatically.

Also, can you mention the features that you can build with? So how to build without asm support, or build for only one bitdepth. That's different from dav1d so it seems appropriate here.

Added.

[thedataking]

LGTM 🚀

nit: One additional target we support is aarch64-linux-android (although running tests in Android is not there yet). Up to you whether to update the readme since we will also be adding x86_64-pc-windows-msvc in the near future.

[randomPoison]

nit: One additional target we support is aarch64-linux-android (although running tests in Android is not there yet). Up to you whether to update the readme since we will also be adding x86_64-pc-windows-msvc in the near future.

I'd say let's hold off on adding it, and add it to the README in the PR that adds CI coverage for it.