Took a first stab at this. I described the addition process in terms
of how it is now, rather than how it will be when we compile
tree-sitter ASTs directly into Core. I anticipate that this will
impress upon the public the amount of work required to add a new
language, and hopefully encourage people to wait until the new
generation of AST parsing lands before they invest a ton of time into
what will be a deprecated code path.
