Update the typecheck.md page to talk about singleton types and their uses, tagged unions.
As a driveby, improve the documentation on type refinements. And delete the unknown symbols part, this is really dated.
* Update docs/_pages/typecheck.md to fix a typo
Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
* Documentation for type packs
* Update docs/_pages/typecheck.md
Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
* Add a note about the difference between ...T and T...
Fix a typo at the start as well.
Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>