[ticket/12677] Replace ‘thread’ with ‘topic’ in functions_display comment

PHPBB3-12677
Merge branch 'k0nsl-ticket/12677' into develop-ascraeus

* k0nsl-ticket/12677:
  [ticket/12677] Replace ‘thread’ with ‘topic’ in functions_display comment
Merge branch 'develop-ascraeus' into develop

* develop-ascraeus:
  [ticket/12677] Replace ‘thread’ with ‘topic’ in functions_display comment