Document the globals in validate_column(), get_sql_for_clause() and build_time_query().

[upadalavipul]

I am checking for all function commenting details for a good & better understanding of the code and in which I have found one file that needs improvement. please check the below details.
File Name: wp-includes/class-wp-date-query.php
Function Name: validate_column(), get_sql_for_clause() and build_time_query()

[SergeyBiryukov]

Thanks for the patch!

[SergeyBiryukov]

In 54765:

Docs: Document the usage of $wpdb global in WP_Date_Query methods.

Follow-up to [25139], [29933], [38280], [38768].

Props upadalavipul.
Fixes #57033.