Operator managed trusted_cluster guide

[bernardjkim]

Closes #22474

This PR adds a guide for how to manage trusted_clusters with the Teleport Operator.

[github-actions]

Amplify deployment status

Branch	Commit	Job ID	Status	Preview	Updated (UTC)
bernard/operator-trusted-cluster-guide	6c9df1c	11	✅SUCCEED	bernard-operator-trusted-cluster-guide	2025-01-11 02:00:57

[ptgott]

I would clarify that we expect each cluster to be on a Linux server, then link to the Linux demo guide. Otherwise, I didn't know "instances" meant "VM instances" until I got a couple items into Step 1.

[rosstimothy]

I don't think "instances" here means VM instance or has anything to do with linux. I believe what this is trying to convey is that in order to set up a trusted cluster that there must be TWO teleport clusters already deployed before the trust relationship can be established.

[rosstimothy]

Do we refer to join tokens as invitation token anywhere else in the docs?

Suggested change

	1. Generate the invitation token by running the following command:
	1. Generate the join token by running the following command:

[bernardjkim]

A lot of the documentation was copied from the main trusted clusters doc https://goteleport.com/docs/admin-guides/management/admin/trustedclusters/.

I'll go ahead and update the wording to use 'join' in that guide as well.

[bernardjkim]

It seems like we use 'invitation token' quite a bit in the docs actually. We might want to address this separately across all our docs.

[hugoShaka]

We've not been very good at consistent naming in the past, but last year we consolidated the terms to "join method", and "join token": https://goteleport.com/docs/reference/join-methods/

You don't have to clean old pages, but it's better to favour the official terms in new pages.

[hugoShaka]

The other guides in the section (user/role, access lists, agentless nodes) are covering all 3 IaC tools: terraform, tctl and the operator. Is it possible to do the same for this guide and use tabs to show the examples for every tool?

Documentation fragmentation is a big issue for out IaC today and most users don't know how to create the basic resources with IaC. Consolidating all IaC tools in the same docs page helps reducing the gaps between IaC methods.