Update to Docsy v0.10.0

[aykevl]

This adds support for light/dark mode, which I've waited for for a while. (I wish we could just make it automatic without menu entry, but this is already better than nothing).

There are a few small visual changes, which I think are generally an improvement:

• Buttons are more square.
• Links now have underscores, for accessibility reasons.
• The ellipsis after "Read more..." on the home page is gone.
• The copyright in the footer has changed slightly.

I did a quick browse through the website and couldn't find any breaking changes.

[aykevl]

And now it actually builds, after a few changes.
It looks like it uses a rather old build environment, @deadprogram do you know anything about that? I had to pick a different Go version because by default it would use Go 1.12.

[deadprogram]

We need to update the netlify.toml file:

I think this is what we need to have in there:

[build.environment]
  HUGO_VERSION = "0.127.0"
  GO_VERSION = "1.21"
  NODE_VERSION = "v20.x"

[aykevl]

@deadprogram I mean the build image: https://docs.netlify.com/configure-builds/overview/#build-image-selection
Apparently this can be configured from the web UI somewhere.

[deadprogram]

I think we are already using the latest image:

[aykevl]

Oh, okay. I think I saw Go 1.12 in there, which is kinda old, but 20.04 ships Go 1.13 so it's not that far off.
Then I think there's nothing we need to update.

(That means this PR is ready for merge in my opinion).

[deadprogram]

OK, now merging. Thanks for the update @aykevl