Remove device trust relationship as an example of token:create permis…

[lsgunn-teleport]

…sions

Previously, device trust was included as an example:

With these permissions, users assigned to the role can generate tokens to enroll
a server, application, or database, establish a trust relationship between a root cluster and a new Teleport Proxy Service or leaf cluster, or configure a device trust relationship for a managed device.

Based on the request:

The ability to create a join token is a sensitive action within Teleport. Currently the role to create join tokens is not scoped, allowing the creation of any type of join token. This means that the same permissions that allow you to join a server also could establish an entire new proxy / leaf, or also establish a Device Trust relationship through MDM (https://github.com/gravitational/teleport.e/pull/1018#discussion_r1156604808). The ability for the joining to influence the configuration and state of your cluster may result in unexpected security concerns, for that reason you should consider the ability to create join token's akin to an administrative role.

This PR removes that example.

[github-actions]

🤖 Vercel preview here: https://docs-7ncpfb54t-goteleport.vercel.app/docs/ver/preview

[public-teleport-github-review-bot]

@lsgunn-teleport See the table below for backport results.

Branch	Result
branch/v12	Failed
branch/v13	Failed
branch/v14	Failed

[lsgunn-teleport]

Change was incorporated into these PRs instead:
#33166
#33165
#33164