Give a bool a bool default value.

[Crell]

The public documentation already has a FALSE default value here, so let's keep in sync.

[cmb69]

The docs are not up to date for PHP 7.2+: https://3v4l.org/1FLnX

PS: relevant commit: aa2282d

[nikic]

This would prevent json_decode($value, options: JSON_OBJECT_AS_ARRAY) from working.

[cmb69]

Documented the proper default value now, so this PR can be closed. Thanks for bringing this up, @Crell!