refactor: repo documentation, crate names

[simbleau]

Changes:

• Introduces the same CHANGELOG we use for vello_svg/velato/bevy_vello. Closes Introduce a changelog #519.
• README: Fixes broken links, doc lints, etc.

[DJMcNab]

Has something changed in the status of #518?
We should try and settle that before doing this renaming

The other changes seem mostly fine, although I find the aversion to title case in the changelog slightly strange

[simbleau]

Has something changed in the status of #518? We should try and settle that before doing this renaming

That is a good callout. My guess was that #518 work fell through the cracks to higher priorities.

@xorgy - Is the rename from vello_svg to demo_svg ok? My motivation was to fix having two vello_svgs around.

The other changes seem mostly fine, although I find the aversion to title case in the changelog slightly strange

I just copied other CHANGELOGs, which don't capitalize. But nonetheless I applied your suggestion, we can use capitals.

[simbleau]

finished rebasing @DJMcNab

[DJMcNab]

Thanks. It'll be good to get changelogs started, even if we've not quite settled on the exact format yet

[DJMcNab]

Thanks!