Fix output to be MDX 3 compliant

[pyjarrett]

Some manual changes were required in ada-lang-io/ada-lang-io@7fa75cb to ensure MDX 3 compliance, these should be integrated to be part of the import tool.

[mgrojo]

The various Ada blocks without correct markup were problems in the Wikibooks source, which I already solved after reviewing the conversion here, so they will be fixed just by running again the import tool.

The others should be ideally solved on this side, but they could also be adjusted in the Wikibooks source, if needed.