deprecations should have documentation examples on conversion

ie a particular deprecation instance across multiple filters should have an id, and ability to associate documentation to the id.

Start by locating the deprecation handling and filter-conversion code, then trace how a single deprecation instance is identified across multiple filters. Determine where documentation examples are maintained and define how an identifier links each instance to its documentation; the work is done when the association is implemented and covered by relevant tests.

Written by the indexing model from the issue text.