[New] Managed PostgreSQL Databases on Akamai Cloud with Terraform (#7260)

* [New] Managed PostgreSQL Clusters on Akamai Cloud with Terraform

* Update keywords

* Update guide slug

* Update description, external links

* Fix blueberry

* Copy edits

* copy edit

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Co-authored-by: jddocs <[email protected]>

Author: nmelehan-akamai