docs: Doc tweaks on transport page

[jabbacakes]

Purpose of this PR

Small follow up PR after #4149 landed in my absence. Mostly just general polish for the transport page.

Jira ticket

N/A

Documentation

• Includes edits to existing public manual documentation.

Testing & QA (How your changes can be verified during release Playtest)

N/A small docs changes only

Up-port

N/A

Backports

N/A

[u-pr]

💡 Harness Review

The revised transport overview improves the organization and links, but its new description overstates guarantees that the supported transport APIs do not provide.

_{Reviewed commit 4809206}

_{🤖 Helpful? 👍/👎}

[michalChrobot]

we will land this in a next patch so should be good enough (users won't start using NGOv3.X before September 16th anyway)

*At the end it will make it in original 3.0.0 release