The method's docblock incorrectly stated it always returned an array,
while in practice it can also return `false`.
This change updates the `@return` annotation to correctly specify `array|false`.
* Updated php.net link for some MemCache properties [skip ci]
* Changed protocol to https for links to php.net in comments
* Changed protocol to https for links to php.net in code
* Changed www.php.net (http) to secure.php.net (https) in comments
* Changed www.php.net (http) to secure.php.net (https) in code
* Changed protocol to https for links to php.net in UPGRADE.md
* Changed protocol to https for links to pecl.php.net in comments
* Changed us.php.net to secure.php.net (https) in comments
* Changed protocol to https for links to php.net in docs
* Changed www.php.net (http) to secure.php.net (https) in docs
* Changed protocol to https for links to pecl.php.net in docs
* Changed ru/jp.php.net to secure.php.net (https) in docs
Don't sure about russian guide: is this links meant to be for guide on russian, or not?