feat: add todo.txt tree-sitter

[Jan9103]

Add support for todo.txt (docs, website).

Since i often use todo.txt for organizing and markdown is already included i wanted to offer upstreaming my config.

The official file extension is .todo.txt, but that doesn't work with helix (and a bunch of other editors) due to the recognition prioritization, therefore i also added the alternative .todotxt extension.

This uses the same tree-sitter as neovim.

[the-mikedavis]

Suggested change

	file-types = ["todo.txt", "todotxt"]
	file-types = [".todo.txt"]

This should work to catch .todo.txt files

[Jan9103]

i tried it and test.todo.txt was not recognised.
as far as im aware this is not fixable without changing the recognition code since it checks the extension first (docs) and only checks other methods if it dosnt match (and .txt is the extension)

[the-mikedavis]

Oh I see, I was thinking that .todo.txt was the full filename

[the-mikedavis]

You could use suffix here, I think that should catch test.todo.txt:

file-types = [{ suffix = ".todo.txt"}, "todotxt"]

[Jan9103]

that worked. pushed a new commit