remove redundant explanation

src/doc/tarpl/vec-into-iter.md

@@ -51,22 +51,7 @@ struct IntoIter<T> {
 }
 ```
 
-One last subtle detail: if our Vec is empty, we want to produce an empty
-iterator. This will actually technically fall out doing the naive thing of:
-
-```text
-start = ptr
-end = ptr.offset(len)
-```
-
-However because `offset` is marked as a GEP inbounds instruction, this will tell
-LLVM that ptr is allocated and won't alias other allocated memory. This is fine
-for zero-sized types, as they can't alias anything. However if we're using
-`heap::EMPTY` as a sentinel for a non-allocation for a *non-zero-sized* type,
-this can cause Undefined Behaviour. Alas, we must therefore special case either
-cap or len being 0 to not do the offset.
-
-So this is what we end up with for initialization:
+And this is what we end up with for initialization:
 
 ```rust,ignore
 impl<T> Vec<T> {