docs: update TODO.md

Author: nooneknowspeter

TODO.md

@@ -1,20 +1,8 @@
 # TODO
 
-- [x] setup zig as standalone toolchain
-- [x] setup nix-shell config with dependencies
-- [x] add build instructions to README.md
-- [x] prepare schema for exercises following learncpp.com
-- [x] drop asdf
-  - [x] use only nix; compilers, runtimes
-  - [x] LSPs, formatters, DAPs
-- [x] fix ownership of directory in the container's shared volume
-- [x] create splash screen (ASCII art) for intro
 - [ ] add REPL feature
-  - [ ] execute per file in order of exercises and chapters; compile until exercise completes then on-to the next
-  - [ ] add hints
-  - [ ] show solution to exercise after completion
-  - [ ] add progress bar
-  - [ ] watch; continuously check and update
+  - [ ] diff and patches; solutions and testing
+  - [ ] watch; continuously check and update fs
 - [ ] add exercises
   - [ ] variables
   - [ ] functions