Missing title splicing on section reference

[dbuenzli]

In ocamldoc if one writes a direct reference to a section ({!sectionid} vs {{!sectionid}linked text}) the section title is spliced into the content. odoc does not do this but instead splices sectionid in the content.

Contrast for example the bullet list here:

http://docs.mirage.io/topkg/Topkg/index.html#basics
http://erratique.ch/software/topkg/doc/Topkg.html#basics