feat(move_semantics): clarify some hints

exercises/move_semantics/move_semantics1.rs

@@ -1,5 +1,5 @@
 // move_semantics1.rs
-// Make me compile! Execute `rustlings hint move_semantics1` for hints :)
+// Execute `rustlings hint move_semantics1` or use the `hint` watch subcommand for a hint.
 
 // I AM NOT DONE
 

exercises/move_semantics/move_semantics2.rs

@@ -1,6 +1,6 @@
 // move_semantics2.rs
 // Make me compile without changing line 13 or moving line 10!
-// Execute `rustlings hint move_semantics2` for hints :)
+// Execute `rustlings hint move_semantics2` or use the `hint` watch subcommand for a hint.
 
 // I AM NOT DONE