[ticket/12489] Add notice about %s wildcard in FIELD_IS_CONTACT_EXPLAIN

PHPBB3-12489
[ticket/12489] Language correction

PHPBB3-12489
Merge pull request #2942 from Senky/ticket/12489

[ticket/12489] Description for Contact link in custom profile fields
[ticket/13136] Update schema.json with latest changes

PHPBB3-13136
[ticket/13137] Remove schema.json file

PHPBB3-13137
[ticket/13137] Generate the schema when the schema.json file is not available

PHPBB3-13137
[ticket/13137] Improve output of create_schema_files.php

PHPBB3-13137
[prep-release-3.1.0-RC5] Update version to 3.1.0-RC5
[prep-release-3.1.0-RC5] Add migration for 3.1.0-RC5
[prep-release-3.1.0-RC5] Prepare Changelog
[prep-release-3.1.0-RC5] Add changelog for 3.1.0-RC5
[prep-release-3.1.0-RC5] Update phpBB Version for RC6 development