[ticket/12519] Restore m_approve language description

Restore acl_m_approve language description to:
"Can approve and restore posts"

PHPBB3-12519
Merge pull request #2452 from n-aleha/ticket/12519

[ticket/12519] Restore m_approve language description

* n-aleha/ticket/12519:
  [ticket/12519] Restore m_approve language description