feat(move_semantics): finish updating comments

exercises/move_semantics/move_semantics4.rs

@@ -1,8 +1,8 @@
 // move_semantics4.rs
-// Refactor this code so that instead of having `vec0` and creating the vector
-// in `fn main`, we create it within `fn fill_vec` and transfer the
-// freshly created vector from fill_vec to its caller.
-// Execute `rustlings hint move_semantics4` for hints!
+// Refactor this code so that instead of passing `vec0` into the `fill_vec` function,
+// the Vector gets created in the function itself and passed back to the main
+// function.
+// Execute `rustlings hint move_semantics4` or use the `hint` watch subcommand for a hint.
 
 // I AM NOT DONE