With the increased cadence of releases it becomes necessary that we address the `WC tested up to` header's usefulness. It isn't practical to require everyone to update their extensions every month, especially given that we are only doing backwards compatible minor releases. The only case I can think of where we might want to check the minor version is if the Stable tag on Core is downgraded, but due to the naming of the header, this doesn't make any sense.
I considered making this a wildcard of some kind but I think most would bind to a full major version anyway and so this isn't worth the time to add it. As an aside, the tests in `plugin-updates.php` seem to indicate that a header of `WC tested up to: 4` would apply to the entire major version cycle, so wildcards already exist!
The documentation of the method
WC_Plugin_Updates::get_untested_plugins() said that it only considers
active plugins when getting the list of untested plugins, but it
actually considers all installed plugins. This commit simply updates the
documentation to reflect the method behavior.