Docs: move documentation for DateTime functions to source code. Part 5.

[Blargian]

Moves documentation for DateTime functions into source code so that we can generate it from system tables. (Part 5).

Changelog category (leave one):

• Documentation (changelog entry is not required)

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

...

Documentation entry for user-facing changes

• [ ] Documentation is written (mandatory for new features)

[clickhouse-gh[bot]]

Workflow [PR], commit [988f4e07]

[clickhouse-gh[bot]]

Workflow [PR], commit [f0b1b01b]

Summary: ❌

job_name	test_name	status	info	comment
Stateless tests (amd_binary, ParallelReplicas, s3 storage)		failure
	02233_HTTP_ranged	FAIL

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