Change missing impl assist to use todo!() instead of unimplemented()

todo!() "Indicates unfinished code" (https://doc.rust-lang.org/std/macro.todo.html)

Rust documentation provides further clarification:

> The difference between unimplemented! and todo! is that while todo!
> conveys an intent of implementing the functionality later and the
> message is "not yet implemented", unimplemented! makes no such claims.

todo!() seems more appropriate for assists that insert missing impls.

1 files changed, 1 insertions, 1 deletions

diff --git a/docs/user/assists.md b/docs/user/assists.md
index 754131f6f..cc42169d8 100644
--- a/docs/user/assists.md
+++ b/docs/user/assists.md
@@ -175,7 +175,7 @@ trait Trait<T> {
 }
 
 impl Trait<u32> for () {
-    fn foo(&self) -> u32 { unimplemented!() }
+    fn foo(&self) -> u32 { todo!() }
 
 }
 ```