update.php documentation

[darkdragon]

I went ahead and documented update.php with the lone function. It was easy and should at least help move any additional functions forward for additional phpdoc documentation.

update.php documentation which adds phpdoc

I think that the documentation in the code should describe the purpose of the function and it's arguments and returns to enable it to be called.

Any extra information like how to disable a feature should not be in the documentation.

That kind of information is better stored in the codex.

Thanks. I'll remove it. The plugin is available in plain sight so yeah, it would be unbiased to remove that text. I'll clean up the rest of it and submit a new patch.

Fixes from Westi suggestion

Finished with Westi suggestion and added patch.

(In [6297]) Add documentation for wp_version_check(). Fixes #5233 props darkdragon.