chore(tvix/docs): Cross off a TODO

This is done now, as of fc6359463 (feat(tvix/repl): Allow binding
variables at the top-level, 2024-07-04)

Change-Id: I2126cbadeb66625cda93a7cd7ddb31409ec60fd9
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11955
Reviewed-by: flokli <flokli@flokli.de>
Autosubmit: aspen <root@gws.fyi>
Tested-by: BuildkiteCI

tvix/docs/src/TODO.md

@@ -89,12 +89,6 @@ Extend the other pages in here. Some ideas on what should be tackled:
 
 ## Features
 
-### CLI
- - `nix repl` can set variables and effectively mutates a global scope. We
-  should update the existing / add another repl that allows the same. We don't
-  want to mutate the evaluator, but should construct a new one, passing in the
-  root scope returned from the previous evaluation.
-
 ### Fetchers
 Some more fetcher-related builtins need work:
  - `fetchGit`