Fix build error and link in PostgreSQL docs

[colebow]

Description

Fix the build error in docs. Double underscore makes these anonymous, so they can share the same name. Technically also works as long as the links are the same, but let's just solve the problem twice. 😄

Non-technical explanation

Release notes

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# Section
* Fix some things. ({issue}`issuenumber`)

[findepi]

Looks like we merged https://github.com/trinodb/trino/pull/14240 failing the build.

[martint]

Tested locally