InnoDB error log messages in MariaDB 10.2 and later should not refer to MySQL 5.7 documentation.
With MariaDB 10.0 and 10.1 it is a little more acceptable to point to the 5.6 documentation, because the features have not yet diverged that much yet.
The InnoDB source code in 10.2 contains the following links that must be replaced with links to the Knowledge Base:
http://dev.mysql.com/doc/refman/5.7/en/operating-system-error-codes.html (non-existing page!)
http://dev.mysql.com/doc/refman/5.7/en/innodb-file-format.html (only used in deprecation messages; we can simply remove this link)
http://dev.mysql.com/doc/refman/5.7/en/innodb-parameters.html (should point to https://mariadb.com/kb/en/mariadb/xtradbinnodb-server-system-variables/ instead)
We need the https://mariadb.com/kb/en/ equivalents of all the links, so that they can be replaced.
I guess that http://dev.mysql.com/doc/refman/5.7/en/ could be directly replaced with https://mariadb.com/kb/en/ or some InnoDB specific page.