Adding enterprise search comments and links to ECK 2.16 docs

[eedugon]

ECK 3.0 still supports Enterprise Search for deployments running 8.x versions of Elastic Stack (and maybe even 7.17, although that's irrelevant for the PR).

We had removed almost all references to Enterprise Search during the migration and that will look odd considering that some users might still run ECK-managed deployments with Enterprise Search.

This PR adds mentions to Enterprise Search in 3 different docs, including links to the 2.16 version of ECK documentation:

• Stack helm chart utilization
• Orchestrating other elastic stack applications
• Network policies examples

Another approach for this would be to bring back all content related to Enterprise Search from older docs, but maybe it's better this way.

@shainaraskas , @bmorelli25 : I'd need to know if the links I'm using for the older documents are correct in terms of destination.

And extra question for doc stakeholders:

• What should we do with URL mappings of those components? For example https://www.elastic.co/guide/en/cloud-on-k8s/current/k8s-enterprise-search.html and all childs have been removed in the new docs system. Should we create redirects or something to point them to the 2.16 version of the docs? or should they all be mapped to the new version of the docs that tells users that Enterprise Search is not supported in 9.x and link to the 2.16 docs?

[shainaraskas]

couple small edits

[shainaraskas]

Another approach for this would be to bring back all content related to Enterprise Search from older docs, but maybe it's better this way.

@leemthompo who owns these docs has been asked not to do this so we'll leave it out for now

@shainaraskas , @bmorelli25 : I'd need to know if the links I'm using for the older documents are correct in terms of destination.

These look fine - explicitly specifying the ECK version will make sure these links are live as long as they're relevant AFAIK

What should we do with URL mappings of those components? For example elastic.co/guide/en/cloud-on-k8s/current/k8s-enterprise-search.html and all childs have been removed in the new docs system. Should we create redirects or something to point them to the 2.16 version of the docs? or should they all be mapped to the new version of the docs that tells users that Enterprise Search is not supported in 9.x and link to the 2.16 docs?

These are currently redirecting to 2.16 and I think that's the right choice. you can see the mappings in this spreadsheet.