List some problems

README.md

@@ -117,3 +117,10 @@ The solution seems to be to run `pip install black pipx` somewhere.
 - Clean up shell script code
 - Be better at "just working"
 - Make it easy to add "private" and alternate formatters
+
+# Problems
+
+- It would probably be better if we wrote reformatted code to temp files and
+  atomically renamed them
+- This probably doesn't work on Windows as-is.
+- It doesn't work with tramp.