Dedicated section in docs explaining Incubator

[vordimous]

depends on https://github.com/aklivity/zilla/issues/670

Describe the desired outcome from the user's perspective Incubator features could be the solution a user wants but needs to see it implemented to validate the usage. Making the explanation and implementation clear will enable them to succeed faster.

Acceptance criteria

• A dedicated landing page for Incubator
• Use the prebuilt incubator resources where appropriate
• All incubator features should be represented

tasks

• [x] Explain what the incubator is and how it is used
• [x] Reference the incubator explanation page with banners and links

[vordimous]

depends on https://github.com/aklivity/zilla/issues/800