Log Message:
Update to 8.5.6

Upstream changes:
Drupal 8.5.6 Release notes

Maintenance and security release of the Drupal 8 series.

This release fixes security vulnerabilities. Sites are urged to upgrade \ 
immediately after reading the notes below and the security announcement:

    Drupal Core - 3rd-party libraries -SA-CORE-2018-005

No other fixes are included.