Documentation about Update URI plugin header directive and its usage

[smileBeda]

What is the new page you are requesting?

A proper documentation with examples about how to use Update URI:

How will this new page help you?

It will not just help me but the plethora of confused developers (see comments in subsequent links)

Current "Documentation"

https://make.wordpress.org/core/2021/06/29/introducing-update-uri-plugin-header-in-wordpress-5-8/
https://make.wordpress.org/core/2020/07/30/recommended-usage-of-the-updates-api-to-support-the-auto-updates-ui-for-plugins-and-themes-in-wordpress-5-5/
https://developer.wordpress.org/reference/hooks/update_plugins_hostname/

Suggested approach

• wait for https://core.trac.wordpress.org/ticket/59631 clarifications
• write up (possibly with help of someone with a bit more insight into the core code) a suggested approach
• provide code examples.

I currently have working solutions but they do not use the new suggested Update URI: nor the new filter update_plugins_{hostname} because they are just dysfunctional at this point. So I prefer to not share them at this point to not further confuse developers.

[github-actions]

Heads up @WordPress/docs-issues-coordinators, we have a new issue open. Time to use 'em labels.