Language Reference page: added contents navigation.

Signed-off-by: Matt Andrews <matt@mattandrews.id.au>
Language Reference page: add includes section.

Signed-off-by: Matt Andrews <matt@mattandrews.id.au>
Language Reference page: remove interactive attrib from includes sample.

Signed-off-by: Matt Andrews <matt@mattandrews.id.au>
Merge pull request #1291 from matthewandrews/gh-pages

Language Reference page: added contents navigation and includes section.