Incorrect @since value for add_allowed_options()

[coffee2code]

In [48121] for WP 5.5, add_option_whitelist() was deprecated and renamed to add_allowed_options(). However, the @since documentation value for the new function was not updated to "5.5.0". The pre-existing value of "2.7.0" only properly applies to add_option_whitelist() and gives the mistaken impression that add_allowed_options() was available for use prior to 5.5.

This looks to just be an oversight as the similar remove_option_allowed_list() (which replaced remove_option_whitelist() in the same commit) has its @since value updated.

Patch attached.

[coffee2code]

Patch mentioned in ticket.

[SergeyBiryukov]

In 49096:

Docs: Correct @since version for add_allowed_options().

Follow-up to [48121].

Props coffee2code.
Fixes #51450.