Mark Rotteveel migrated the first documents to asciidoc

Mark Rotteveel and documentation team migrated the first documents to asciidoc

– Docbuilding Howto
https://www.firebirdsql.org/file/documentation/html/en/firebirddocs/docbuildhowto/firebird-docbuilding-howto.html
– Docwriting Guide
https://www.firebirdsql.org/file/documentation/html/en/firebirddocs/docwritehowto/firebird-docwriting-guide.html

ps: Since May/June 2020, the Firebird documentation project has switched to AsciiDoc for its documentation. This section gives a short overview how AsciiDoc is used by the project.