clarify transition path

Author: Gankra

active/0000-raw-reform.md

@@ -165,8 +165,8 @@ following refactors:
 
 * Deprecate all of `slice::raw` as poorly motivated, especially with raw slices available.
 
-* Deprecate all unsafe methods on the `ImmutableSlice` and `MutableSlice` extension traits
-in favour of using raw slices.
+* Deprecate `ImmutableSlice::unsafe_get` and `MutableSlice::unsafe_mut` in favour of using raw
+slices and indexing into them.
 
 * Add `as_raw` and `as_raw_mut` to the `Slice` and `MutSlice` extension traits.
 
@@ -185,6 +185,11 @@ In addition, this would have the benefit of removing the need to explicitly cast
 
 * Make the RawPtr traits take self by value, because ptrs are `copy`.
 
+When all of this is done, slices will no longer have *any* unsafe methods. This clearly delinates
+slices as "the safe way" and raw slices as "the unsafe way". The naive transition path will be
+`foo.unsafe_get(i)` -> `foo.as_raw()[i]`. However if lots of unsafe work needs to be done, the
+`as_raw` conversion need only be done once.
+
 The ptr module ends up only having the following functions:
 
 ```