Backport of docs: Updates to support HCP Consul cluster peering release into release/1.15.x (#16809)
* backport of commit a04e4762a2
* backport of commit 05702b5b59
* docs: Updates to support HCP Consul cluster peering release (#16774)
* New HCP Consul documentation section + links
* Establish cluster peering usage cross-link
* unrelated fix to backport to v1.15
* nav correction + fixes
* Tech specs fixes
* specifications for headers
* Tech specs fixes + alignments
* sprawl edits
* Tip -> note
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Co-authored-by: boruszak <jeffrey.boruszak@hashicorp.com>
Co-authored-by: Jeff Boruszak <104028618+boruszak@users.noreply.github.com>
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