Adds changes to the applies_to page

[charlotte-hoblik]

Preview: https://docs-v3-preview.elastic.dev/elastic/docs-builder/pull/1325/syntax/applies

Update applies_to page to match new versioning guidelines. Removed outdated parts and added missing info.

[leemthompo]

Thanks @charlotte-hoblik your changes about the updates look great, I just think we should take the opportunity to improve the overall structure of the page now that the information is more mature. I didn't give this a 100% thorough review, but should be enough to build upon your work.

[leemthompo]

I think we can restructure the page now that we have more info and have more logical progression:

Something like:

1. Intro
2. Syntax
3. When and where to use applies_to ← new grouped section

• Intro/explain that each level has slightly different syntax.
• Mention stuff currently in 'when to use'
• Levels:
  • Page-level (required)
  • Section-level
  • Inline

5. Structured model (Maybe could have better heading name like "Metadata structure" or something)
6. Examples

I'm not married to any specific ordering here apart from having more context and explanations up top. :)

[leemthompo]

and maybe we can weave examples into other sections and remove the standalone examples #maybe

[leemthompo]

@charlotte-hoblik I think we could improve the flow in the Syntax section, namely by moving lifecycle up higher:

• Basic pattern
• Life cycle
• Version
• Combined states

[charlotte-hoblik]

Thank you, @leemthompo for the helpful feedback and suggestions!
Heads-up: the examples are still a work in progress, with more updates coming.