gvarianttype: Add two missing (nullable) annotations and port docs to gi-docgen format
Spotted while working on the docs (see the following commit).
Convert docs to gi-docgen linking syntax and improve formatting in a few places while I’m there:
- Add quotes around ‘maybe’ types to make it clearer that ‘maybe’ is being used as a proper noun
- Add linebreaks so that all doc comments start with a single-sentence summary of the method
- Improve formatting of constants
- Add a few links to external specifications
See https://developer.gnome.org/documentation/guidelines/devel-docs.html
Signed-off-by: Philip Withnall pwithnall@gnome.org
Helps: #3250